FOR  TEACHERS 

TO  ACCOMPANY 
ELEMENTARY  BIOLOGY  " 

v 

GRUENBERG 


GIFT   OF 
Agricultural  Educ.Div. 


THWF  n- 


BIOLOGY 

LIBRARY 

G 


MANUAL  OF  SUGGESTIONS 
FOR  TEACHERS 


TO  ACCOMPANY 


"ELEMENTARY  BIOLOGY" 


BY 

BENJAMIN  C.  GRUENBERG 


n  »  >  „  >       ••  n   ,     •       •»     » 


•}    '•. 

v 


GINN  AND  COMPANY 

BOSTON     •     NEW   YORK     •     CHICAGO     •     LONDON 
ATLANTA     •     DALLAS     •     COLUMBUS     •     SAN    FRANCISCO 


BIOLOGY 

LIBRARY 

G 


MAIN  LI«KAKV.A<imCUCttme  DEFT. 


COPYRIGHT,  1919,  KY 
BENJAMIN  C.  GRUENBERG 


ALL   RIGHTS    RESERVED 
319.9 


•• 


atftcnaum 


GINN  AND  COMPANY  •  PKO 
PRIETORS  '  BOSTON  '  U.S.A. 


PREFACE 

This  manual  is  intended  to  aid  the  teacher  in  organizing  in- 
struction material  and  ideas  for  effective  presentation  in  connec- 
tion with  the  author's  "  Elementary  Biology."  It  is  no  substitute 
either  for  a  knowledge  of  the  subject  matter  or  for  the  technique 
of  teaching. 

Since  the  text  which  the  manual  is  to  accompany  is  largely 
concerned  with  showing  how  a  knowledge  of  living  things  helps 
human  beings,  the  notes  here  offered  are  largely  concerned  with, 
suggesting  interpretations  and  applications.  The  method  of  treat- 
ment implied  throughout  assumes  a  changing  body  of  knowledge 
tor  the  teacher,  and  a  changing  civic  and  intellectual  environment 
for  the  pupil.  New  problems  and  new  needs  calling  for  additional 
knowledge,  new  discoveries  enlarging  the  horizon,  new  thought 
bringing  new  insight  and  new  significance  —  these  represent  the 
permanent  stream,  to  be  surveyed  in  its  main  ramifications  even 
while  it  flows.  This  means  imagining  as  well  as  remembering,  it 
means  doubting  as  well  as  believing,  but  it  means  also,  of  course, 
learning  much  more  outside  the  book  than  in  it. 

The  references  are  all  useful ;  but  even  the  most  specific  and 
authoritative  are  transients.  Here  the  intention  is  to  guide  teacher 
and  pupil  to  the  use  of  the  printed  page  with  some  judgment  as 
to  relative  values.  It  is  assumed  that  there  will  be  available  mono- 
graphs and  encyclopedias,  manuals  for  the  identification  of  various 
groups  of  plants  and  animals,  textbooks,  and  current  publications 
of  all  sorts. 

The  teacher  should  be  constantly  on  the  lookout  for  develop- 
ments that  suggest  new  problems  and  new  applications  in  which 
biology  is  significant.  Many  lines  of  publication  are  currently 
available  for  the  mere  asking  ;  others  have  to  be  ordered  as  they 

iii 

674620 


iv  MANUAL  FOR  TEACHERS 

appear.  There  should  be  in  every  high-school  or  college  library 
the  monthly  circular  of  new  publications  issued  by  the  United 
States  Department  of  Agriculture;  the  one  from  the  Public 
Health  Service ;  and  the  one  from  the  Bureau  of  Education. 
The  local  and  state  departments  of  health  and  of.  agriculture,  the 
nearest  Experiment  Station,  the  Bureau  of  Fisheries,  and  similar 
agencies  may  be  drawn  upon  for  helpful  and  pertinent  material. 
And  every  teacher  should  keep  within  hailing  distance  of  what 
appears  in  the  technical  journals.  B  C  G 


MANUAL  FOR  TEACHERS 


PART  I.    THE  WORLD   IN       jCR  WS-'    lVE 

I.  INTRODUqXiOK      V£ 

Ask  pupils  to  report  such  examples  as  they  may  happen  to  have 
of  applied  biology  ;  that  is,  of  practical  use  being  made  of  knowledge 
or  understanding  about  living  things.  The  history  of  civilization  is 
a  continuous  record  of  the  displacement  of  superstition  by  insight. 
Get  examples  of  superstitions  that  have  to  do  with  health  and 
disease  ;  with  the  phases  of  the  moon  in  relation  to  crop  production  ; 
with  lucky  and  unlucky  signs  in  relation  to  fishing  and  hunting 
or  the  performance  of  other  practical  tasks.  Why  do  we  call  these 
beliefs  superstitions,  and  how  do  we  distinguish  them  from  our 
own  true  beliefs  ? 

Have  a  committee  of  two  or  three  students  prepare  a  composite 
list  of  all  the  examples  that  have  been  submitted,  with  some  classi- 
fication of  the  material. 

Have  students  bring  together  what  they  can  of  the  usages  of 
former  generations  with  relation  to  epidemics  and  other  diseases  ; 
with  relation  to  insuring  good  crops,  etc.  Compare  the  average 
length  of  life  and  the  death  rates  at  various  periods  and  in  dif- 
ferent countries.  Compare  yields  per  acre  of  various  crops  at 
different  periods  and  in  different  countries.  How  have  these 
changes  come  about  ?  How  have  they  been  brought  about  ? 

References.  LOCY,  W.  A.,  Biology  and  its  Makers,  pp.  1-8.  WHITE, 
ANDREW  D.,  Warfare  of  Science  and  Theology,  chap.  i.  Yearbooks  of 
the  United  States  Department  of  Agriculture.  Annual  Reports  of  the 
State  Department  of  Health  ;  City  Board  of  Health  ;  Surgeon  General, 
United  States  Public  Health  Service;  Surgeon  General,  United  States 
Army.  «  National  Vitality,"  Bulletin  No.  30  of  the  Committee  of  One 
Hundred  on  National  Health,  Government  Printing  Office.  Work  of 
Vesalius.  Life  and  work  of  William  Harvey. 


MANUAL  FOR  TEACHERS 


II.  WHAT  GOES  ON  IN  THE  WORLD 

The  purpose  of  these  lessons  is  to  acquaint  the  pupils  with 
some  of  the  common  physical  and  chemical  processes.  Some  of 
these  are  directly  concerned  in  vital  processes ;  others  are  helpful 
toward  aii^underst^din^  pf  more  complex  relations.  Incidentally, 
we  may, lay  the  foundations  of  whatever  thinking  our  pupils  are 
capable,  pf ;  sttta{n{«g:  by  introducing  the  first  laws  of  matter  and 
motion,  and  the  idea  of  evolution  in  the  broad  sense  of  continuity 
and  causality.  Where  students  have  already  studied  elementary 
science  this  part  may  be  omitted,  or  perhaps  reviewed  briefly. 

The  laboratory  work  should  be  in  the  nature  of  demonstrations, 
rather  than  experiments  in  the  strict  sense.  The  first  few  lessons 
might  well  be  carried  out  with  the  text  in  the  hands  of  the  pupils, 
and  the  exercises  completed,  or  at  any  rate  started,  in  the  class. 

Things  change.  After  reading  section  7,  have  the  pupils  divide 
a  sheet  of  paper  into  four  columns,  headed  as  below : 


WEATHER 

PLANTS 

HUMAN  BEINGS  AND 
OTHER  ANIMALS 

NON-LIVING  OBJECTS 

In  each  column  are 'to  be  listed  as  many  kinds  of  changes  as  the 
pupils  can  think  of  that  happen  to  the  kinds  of  things  suggested 
by  the  heading  of  the  column. 

Physical  changes.  Section  8  may  be  illustrated  by  melting  a 
lump  of  ice  in  a  pan,  through  applying  the  flame  of  an  alcohol  or 
Bunsen  lamp.  After  calling  attention  to  the  change,  the  heat  is 
again  applied  until  the  water  is  all  gone.  Melt  a  piece  of  paraffin 
or  a  bit  of  candle  and  continue  to  heat,  without,  however,  starting 
decomposition  or  igniting. 

Make  three  lists  of  substances  with  which  you  are  acquainted.  In 
the  first  list  place  the  names  of  those  that  may  exist  in  all  three  states ; 
in  the  second,  those  that  exist  in  only  two  states;  and  in  the  third, 
those  that  exist  in  only  one  state. 


MANUAL  FOR  TEACHERS  3 

Note  that  the  metal  mercury  is  liquid  at  ordinary  temperatures,  and 
that  practically  all  metals  may  be  volatilized  at  high  temperatures. 

Demonstrate  solution  by  placing  sugar,  salt,  marble,  starch,  etc. 
in  tumblers  of  water. 

Chemical  changes.  Prepare  three  large  test  tubes  or  tumblers, 
a  solution  of  washing  soda  (about  four  tablespoons  to  the  pint),  a 
solution  of  barium  chloride,  a  solution  of  phenolphthalein,  and 
some  dilute  hydrochloric  acid.  Before  the  class  call  attention  to 
the  similarity  in  appearance  of  the  four,  solutions.  That  they  are 
not  really  the  same  kind  of  stuff  is  to  be  demonstrated.  Place  the 
soda  solution  in  the  three  test  tubes ;  in  succession  add  portions 
of  the  three  other  solutions.  You  will  obtain  a  precipitate,  a 
change  in  color,  and  an  effervescence.  The  three  distinct  reactions 
indicate  the  occurrence  of  chemical  changes. 

Have  the  pupils  describe  these  examples  of  chemical  change, 
not  in  terms  of  the  materials  used  and  the  materials  produced, 
but  in  terms  of  the  phenomena  observed.  Two  apparently  similar 
liquids  produce,  when  mixed,  a  solid,  insoluble  substance  and  a 
new  liquid,  —  one  that  can  be  shown  to  have  properties  different 
from  those  of  either  of  the  two  used  in  the  first  place.  Two  others 
produce  some  gas,  and  so  on.  It  is  possible  in  each  case  to  show 
that  some  distinct  kind  of  substance  has  disappeared  and  that 
some  new  kind  of  substance  has  been  formed. 

Demonstrate  the  reversibility  of  the  chemical  changes  manifested 
when  a  solution  containing  litmus  or  phenolphthalein  is  alternately 
changed  from  acid  to  alkali  and  the  reverse.  Use  dilute  HC1  and 
dilute  NaOH  solution.  Have  students  suggest  all  the  examples 
of  color  changes  with  which  they  are  familiar ;  some  of  these  will 
be  chemical  changes. 

Have  students  give  examples  of  chemical  changes  that  have  not 
yet  been  brought  to  the  attention  of  the  class.  Make  as  complete 
a  list  as  possible  of  physical  changes  and  one  of  chemical  changes. 

Get  a  committee  of  students  to  compile  the  lists  of  the  whole 
class,  indicating  the  number  of  times  each  particular  kind  of  change 
is  mentioned  and  bringing  in  for  class  discussion  and  conclusion 
all  doubtful  cases. 


4  MANUAL  FOR  TEACHERS 

Complexity  of  matter.  Use  magnifying  glasses  and  bits  of 
granite,  gneiss,  marble,  and  other  minerals  to  get  the  idea  of 
heterogeneity,  —  not  necessarily  the  word. 

Milk  may  be  analyzed,  to  show  that  it  is  made  up  of  several 
distinct  parts.  The  specimen  of  milk  is  allowed  to  stand  over- 
night in  a  four-ounce  wide-mouthed  bottle,  covered  against  dust. 

The  cream,  oifat,  sepa- 
rates out.  In  regions 
that  are  acquainted  with 
dairy  processes,  the  time 
may  be  shortened  by  the 
use  of  a  centrifuge,  or 
separator.  If  the  milk 
has  not  soured,  and  there 
is  nothing  to  be  gained 
by  delaying  the  demon- 
stration, the  milk  may 
be  immediately  curdled 
by  the  addition  of  a  few 
drops  of  acetic  or  some 
diluted  mineral  acid. 
(The  casein  is  held  in 
solution  by  the  natural 

alkalinity  of  the  milk,  and  is  precipitated  on  neutralizing  or  acidi- 
fying.) Separate  the  curd  and  the  whey  by  filtering  through  paper. 
The  whey  may  be  further  analyzed  by  evaporating  over  a  flame, 
in  a  porcelain  dish.  This  shows  the  whey  to  be  made  up  of  water 
and  solid.  The  solid  residue  may  now  be  further  broken  up  by 
ignition,  showing  that  it  is  made  up  of  a  part  that  can  burn  and 
a  part  that  cannot  burn,  —  the  ash. 

Have  pupils  make  a  list  of  the  fractions  of  the  milk  that  can  be 
readily  recognized  as  distinct,  —  as  fat,  curd,  water,  solids-in-whey-that- 
can-burn,  ash. 

Have  ready  for  inspection  specimens  of  alcohol,  ether,  benzine, 
gasoline,  etc.  as  examples  of  liquids  that  appear  to  be  homogeneous ; 


FIG. 


MANUAL  FOR  TEACHERS 


c 


and  rock  candy,  a  lump  of  glass,  and  a  clear  crystal  of  quartz 
or  alum  as  examples  of  solids  that  appear  to  be  homogeneous. 

Wherever  it  can  be  managed,  it  is  worth  while  to  demonstrate 
electrolysis  of  water,  with  a  test  of  each  of  the 
two  gases  produced.  If  a  eudiometer  is  not 
available,  set  up  two  large  test  tubes,  filled  with 
the  acidulated  water,  over  the  two  poles  of  a 
direct-current  system  (see  Fig.  i). 

If  you  have  a  eudiometer,  burn  the  hydrogen 
from  a  small  glass  jet  and  collect  the  vapor  in  a 
cold  bell  jar  or  battery  jar  held  above  the  flame. 

Elements  and  compounds.  Have  a  collection 
of  elements ;  these  can  usually  be  borrowed  from 
the  chemical  laboratory.  The  pupils  should  see 
elementary  sulfur,  phosphorus,  carbon,  sodium 
or  potassium,  iodin,  iron,  magnesium,  and 
silicon.  It  is  not  difficult  to  get  specimens  of 
platinum,  gold,  silver,  nickel,  aluminum,  lead, 
tin,  copper,  and  zinc. 

Energy ;  energy  and  matter.  Reexamine  the 
first  list  of  changes  prepared,  or  the  list  of 
physical  and  chemical  changes ;  next  to  each 
item  of  change  have  students  write  the  name 
of  the  kind  of  energy  that  brings  the  change 
about.  Heat  has  already  been  shown  to  cause 
changes  in  state ;  it  produces  motion,  as  in  the 
thermometer.  This  can  be  demonstrated  on  a 
large  scale  by  gently  heating  a  flask  full  of 
water  closed  by  a  pierced  stopper  carrying  a 
glass  tube  (see  Fig.  2).  A  little  red  or  blue 
ink  may  be  added  to  the  water  to  make  it 
visible  in  all  parts  of  the  room.  Magnetism  may  be  demonstrated 
with  an  electromagnet  or  with  a  permanent  magnet  (bar  or  horse- 
shoe). The  other  forms  of  energy  mentioned,  with  the  excep- 
tion perhaps  of  the  X  rays,  have  either  been  studied  before  or 
may  now  be  demonstrated,  so  far  as  needed. 


FIG.  2 


6  MANUAL  FOR  TEACHERS 

Students  should  get  the  idea  that  all  events  are  connected  in 
series,  and  this  study  may  well  end  by  having  them  describe,  in 
writing,  one  or  two  chains  of  happenings,  in  which  the  change 
in  energy  as  well  as  the  change  in  matter  is  indicated  for  each  link. 

Conservation  of  energy.  Many  children  come  to  school  with  the 
superstition  that  machines  are  devices  for  increasing  the  amount 
of  energy.  It  is  well  to  clear  up  any  misgivings  or  misunder- 
standings on  this  point.  Machines  vary  as  to  efficiency,  —  that 
is,  as  to  the  proportion  of  all  the  energy  they  receive  that  they 
make  available  in  the  special  work  for  which  they  are  intended, 
—  but  in  all  machines  the  output  of  energy  is  exactly  equal  to 
the  income. 

References.  PEARSON,  KARL,  Grammar  of  Science,  chap.  i.  Have 
students  report  on  readings  in  any  accessible  textbooks  in  physics,  chem- 
istry, or  general  science  on  such  topics  as  physical  changes,  chemical 
changes,  work,  states  of  matter,  conservation  of  matter,  conservation  of 
energy,  elements,  compounds,  forms  of  energy,  transformation  of  energy, 
perpetual  motion,  the  philosophers'  stone,  efficiency,  etc. 

III.    FIRE 

The  concern  of  the  student  of  life  with  fire  is  sufficiently  indi- 
cated in  the  text.  The  experiment  suggested  in  section  1 7  is  not 
practicable  for  the  ordinary  laboratory,  and  would  not  in  any  case 
convince  the  skeptic. 

Air  and  fire.  Here  we  meet  problems  that  lend  themselves 
readily  to  experimental  treatment,  and  the  opportunity  should  be 
utilized  to  make  clear  the  method  of  the  experiment.  A  candle  flame 
furnishes  the  most  convenient  "  fire  "  for  these  experiments,  and 
a  Bunsen  or  an  alcohol  flame,  or  both,  will  be  convenient  to  have 
at  hand. 

The  flicker  of  the  flame  suggests  that  burning  liberates  motion 
in  addition  to  light  and  heat,  but  it  may  well  be  that  this  motion 
is  imposed  upon  the  flame  by  air  currents,  as  is  the  case  with 
the  trembling  of  leaves,  for  example,  or  the  movement  of  the  shirt 
on  the  clothesline.  Here  we  may  find  out  by  trying,  that  is,  by 
experiment.  Emphasize  the  important  fact  that  we  have  here  a 


MANUAL  FOR  TEACHERS  / 

problem  the  solution  of  which  we  shall  seek  not  in  authorities,  or 
in  the  records  of  other  people's  beliefs  and  opinions,  but  in  the 
materials  and  forces  at  hand.  Have  the  problem  formulated  clearly 
by  the  pupils,  that  there  may  be  no  ambiguity  as  to  just  what  we 
are  trying  to  find  out.  How,  then,  shall  we  find  out?  A  second 
item  involves  the  use  of  various  materials.  Record  should  be  made 
of  the  things  used.  Then  what  is  to  be  done  with  the  things  ?  The 
generalized  scheme  for  the  experiment  is,  to  shut  off  air  currents. 
Many  suggestions  may  be  made  by  the  pupils,  and  the  suggestions 
will  in  turn  be  criticized.  There  should  be  substantial  agreement 
on  the  most  reasonable  or  the  most  convenient  method  to  be 
pursued  or  material  to  be  used.  A  lamp  chimney 1  has  the  advan- 
tage that  it  may  surround  the  flame  on  all  sides,  and  that  it  is  trans- 
parent. Produce  the  lamp  chimney  and  set  it  over  the  burning 
candle.  The  flickering  stops,  and  this  result  may  be  sufficient  to 
satisfy  the  pupils  with  the  conclusion  that  the  flicker  is  due  to  out- 
side disturbances.  If  there  is  any  disposition  to  discuss  the  matter 
further,  be  careful  to  remove  the  chimney  before  the  flame  is  ex- 
tinguished ;  it  may  be  put  on  and  taken  off  several  times  before 
the  question  is  closed.  As  the  discussion  nears  its  end,  leave  the 
chimney  over  the  candle,  and  the  flame  will  expire.  This  will  at 
once  suggest  new  issues,  and  many  of  the  pupils  will  be  prepared 
to  explain  that  it  is  the  exclusion  of  the  air  that  resulted  in  the 
dying  out  of  the  flame.  But  before  that  can  be  taken  up,  make 

1  In  general  it  is  well  to  have  the  materials  to  be  used  in  the  day's  work 
readily  accessible  in  the  laboratory  or  recitation  room,  but  not  laid  out. 
When  you. —  that  is,  the  teacher  and  the  pupils  —  decide  that  a  lamp 
chimney  would  be  desirable,  the  teacher's  resources  must  be  equal  to  the 
occasion.  But  no  matter  how  carefully  the  teacher  has  prepared  the  day's 
demonstration,  the  procedure  should  never  give  the  impression  of  being 
"  cut  and  dried  "  in  advance.  Exception  should  be  made  for  demonstra- 
tions that  involve  rather  elaborate  arrangements,  or  that  take  more  time 
for  setting  up  than  the  usual  session  allows.  In  that  case,  however,  there 
is  either  no  pretense  that  the  experiment  is  performed  in  response  to  a 
problem  that  has  arisen  in  the  class,  or,  if  you  have  led  up  to  the  problem, 
the  plans  for  the  experiment  may  be  agreed  upon  at  one  session,  with  the 
understanding  that  the  preparations  will  be  made  in  anticipation  of  a  future 
meeting  of  the  class. 


8  MANUAL  FOR  TEACHERS 

a  complete  record  of  the  first  experiment,  insisting  upon  the  logical 
sequence  and  clear  analysis  rather  than  upon  the  mechanical  form 
of  the  record.  These  points  should  stand  out  clearly,  whatever 
designations  may  be  used: 

1 .  The  problem  :  the  question  to  be  solved. 

2.  Materials  and  apparatus :  what  was  used. 

3.  Operations  performed :  what  was  done. 

4.  Results :  what  happened,  what  phenomena  were  observed. 

5.  Conclusions}:  the  answer  to  the  question,  so  far  as  it  may  be 
inferred  from  the  results. 

In  insisting  upon  a  correct  record  of  the  first  experiment,  we 
must  shift  the  emphasis  from  the  performance,  as  an  interesting 
"  stunt,"  to  the  argument  involved  in  formulating  the  problem, 
in  selecting  materials  and  operations,  in  selecting  the  significant 
elements  from  the  results,  and  in  drawing  conclusions. 

When  we  have  established  this  routine  of  thinking  about  ex- 
periments, less  time  will  be  required  in  the  .matter  of  form  of 
records  etc. 

The  second  experiment,  suggested  by  the  expiration  of  the 
flame,  centers  on  the  question  whether  the  flame  uses  tip  something 
in  the  air  or  gives  off  something  that  interferes  with  burning.  The 
air  being  invisible,  we  must  have  some  means  of  showing  the  in- 
crease or  decrease  in  the  volume  of  air.  It  may  be  that  after 
several  suggestions  from  the  pupils,  it  will  devolve  upon  the  teacher 
to  find  a  feasible  plan.  A  cylinder  large  enough  to  go  over  the 
candle,  and  closed  at  one  end,  inserted  over  the  lighted  candle 
standing  in  a  dish  of  water,  will  meet  all  the  conditions.  If  the 
flame  gives  off  gas(es),  bubbles  should  be  forced  through  the  water, 
out  of  the  cylinder ;  but  if  the  flame  uses  up  part  of  the  air,  what 
would  happen  ?  The  possible  results  should  be  anticipated  as  part 
of  the  argument,  before  the  operation  is  actually  performed,  but 
with  the  apparatus  in  hand. 

Some  of  the  pupils  will  probably  jump  to  the  conclusion  that 
the  flame  uses  up  part  of  the  air.  But  we  must  not  be  too  sure. 
It  is  quite  conceivable  that  both  processes  are  going  on  at  the 


MANUAL  FOR  TEACHERS  9 

same  time,  but  at  different  rates.  Here  is  a  problem  for  the 
chemist  —  to  identify  the  gases  concerned. 

When  the  cylinder  is  finally  placed  over  the  lighted  candle,  the 
flame  begins  to  fade,  it  flickers  a  few  times,  and  finally  expires.  In 
the  meantime  the  level  of  the  water  inside  the  cylinder  changes 
in  a  way  that  indicates  a  reduction  in  the  amount  of  gas  included. 
We  may  also  observe  the  condensation  of  moisture  on  the  inside 
of  the  cylinder,  and  the  ascent  of  the  thin  column  of  smoke  from 
the  wick.  Which  are  the  phenomena  that  are  significant  in  relation 
to  our  problem  ?  Obviously,  the  change  in  level  of  the  water. 
What  does  that  show  ?  Probably  that  something  in  the  air  has 
been  removed  by  the  action  of  the  flame.  By  means  of  a  ruler 
held  alongside  the  cylinder  it  may  be  possible  to  get  an  approxi- 
mate idea  of  what  proportion  of  the  air  has  been  thus  used  up. 

But  let  us  not  overlook  the  possibility  that  something  may  be 
present  in  the  jar  (the  air)  that  was  not  there  before.  We  shall 
have  to  come  back  to  the  question  whether  the  flame  gave  off 
something.  There  is  the  smoke,  for  example ,'  and  perhaps  there 
are  some  invisible  fire  products.  We  may  need  the  assistance  of 
the  chemist  to  answer  the  question.  At  this  time  we  may  be  cer- 
tain only  that  something  has  been  taken  from  the  air  by  the  burning. 

Now  as  to  the  chemical  nature  of  the  remaining  gas  (or  mixture 
of  gases),  we  should  need  some  knowledge  of  chemistry  to  pro- 
ceed farther.  It  is  futile  to  test  this  air  further  with  relation  to 
fire,  as  some  of  the  students  are  almost  sure  to  suggest ;  for 
the  failure  of  a  flame  to  burn  in  this  residual  air  cannot  tell  us 
anything  that  we  did  not  already  know.  The  teacher,  drawing 
upon  his  fuller  experience,  produces  a  reagent,  a  substance  that 
reacts  distinctively  with  the  various  gases  —  in  this  case  lime- 
water.  Yes,  it  is  the  same  kind  of  limewater  as  is  sometimes  used 
in  the  baby's  milk  bottle.  It  is  prepared  by  shaking  up  some 
calcium  oxid  (unslaked  lime)  with  water,  and  filtering  through 
paper.  This  should  be  kept  .in  tightly  stoppered  bottles  (cork  is 
better  than  glass ;  but  if  glass-stoppered  bottles  are  used,  smear 
a  little  vaseline  on  the  stopper,  to  make  sure  of  an  air-tight  joint 
that  will  not  become  caked).  A  little  limewater  is  placed  in  the 


10  MANUAL  FOR  TEACHERS 

bottom  of  a  cylinder  similar  to  the  one  used  in  the  experiment. 
Place  a  glass  plate  or  the  palm  of  the  hand  over  the  open  end 
of  the  cylinder  and  shake  up  vigorously.  The  limewater  does  not 
change  its  appearance  perceptibly.  A  little  limewater  is  placed  in 
the  cylinder  in  which  the  flame  had  expired,  the  cylinder  being 
quickly  turned  up  and  then  quickly  covered.  When  the  limewater 
is  shaken  up,  it  turns  cloudy  or  milky.  This  shows  us  at  least 
that  the  two  masses  of  air  are  different,  although  it  does  not  tell 
us  just  what  the  difference  is.  We  may  therefore  conclude  that 
the  burning  process  not  only  removes  something  from  the  air 
but  also  sets  free  something  that  was  not  there  before. 

The  question  may  here  be  raised  as  to  the  relation  between  the 
products  of  combustion  to  the  fuel,  on  the  one  hand,  and  to  the 
materials  removed  from  the  air,  on  the  other. 

Burning  a  synthesis.  It  is  a  reasonable  hypothesis  that  the 
product,  like  the  visible  ash  of  some  other  fires,  is  either  some 
portion  of  the  fuel  thus  set  free,  or  a  portion  of  the  fuel  or  of 
the  air  modified  in  some  way,  or  a  new  combination  of  materials, 
containing  elements  from  the  fuel,  from  the  air,  or  from  both. 

The  technique  of  testing  these  variations  of  the  hypothesis  is 
rather  too  complex  for  the  schoolroom.  We  can,  however,  test  the 
supposition  that  the  product  of  a  burning  contains  fuel  substance 
plus  air  substance.  For  this  purpose  we  must  have  a  fuel  the 
burning  of  which  gives  us  a  product  that  is  easily  gathered  and 
weighed.  We  use  magnesium  ribbon,  —  magnesium  because  the 
product  of  its  combustion  is  solid,  and  ribbon  because  it  is  con- 
venient to  handle. 

A  trip  balance  has  a  large  funnel,  closed  with  cotton  wool  in 
the  stem,  on  one  platform,  with  a  strip  of  ribbon  about  eight 
inches  long.  This  is  counterbalanced  until  the  platforms  are  level. 
A  wire  loop  or  hook  may  be  hung  into  the  funnel  before  adjusting 
the  balance.  The  magnesium  ribbon  is  hung  from  the  loop  and 
ignited  with  an  alcohol  or  Bunsen  flame,  and  the  funnel  is  imme- 
diately replaced  upon  the  platform  of  the  scale.  If  the  operation 
has  been  carefully  conducted,  the  accumulated  smoke  or  ashes  will 
be  found  to  weigh  more  than  the  original  ribbon  of  magnesium. 


MANUAL  FOR  TEACHERS 


II 


Since  the  addition  to  the  solid  matter  on  the  scale  platform  could  have 
come  only  from  the  air,  we  are  tempted  to  conclude  that  the  air 
stuff  that  takes  part  in  burning  combines 
with  something  in  the  fuel. 

The  gases  in  the  air.  The  three  principal 
gases  of  the  atmosphere  may  be  prepared 
for  laboratory  use  as  follows : 

Carbon  dioxid.  A  wide-mouthed  bottle 
or  flask  is  fitted  with  a  two-holed  stopper. 
Into  one  hole  is  fitted  a  glass  "thistle" 
tube  reaching  nearly  to  the  bottom  of  the 
bottle.  Into  the  other  hole  is  fitted  a  bent 
glass  tube  reaching  only  a  fraction  of  an 
inch  below  the  cork  or  rubber  and  having 
a  rubber  tube  attached  to  the  outside  arm 
(Fig.  3).  This  apparatus,  or  gas  genera- 
tor, may  be  used  for  generating  hydrogen 
and  for  other  purposes.  To  make  carbon 
dioxid,  place  some  marble  chips  (calcium 
carbonate)  or  limestone  bits  in  the  bottom 
of  the  bottle  ;  insert  the  stopper  with  the 
tubes  and  pour  water  through  the  thistle 
tube  until  the  chips  are  covered.  Pour 
dilute  hydrochloric  acid  (commercial  will 
do)  slowly  into  the  thistle  tube  until  effer- 
vescence begins.  Place  the  free  end  of 
the  rubber  delivery  tube  in  a  pneumatic 
trough  or  in  a  dish  of  water.  The  bubbles 
coming  through  the  water  indicate  the  rate 
at  which  gas  is  being  liberated.  Carbon 
dioxid  can  be  collected  either  with  the 

help  of  a  pneumatic  trough  or  with  a  large  dish  of  water,  the 
tubes  or  bottles  to  be  filled  being  held  in  the  hand  over  the 
delivery-tube  opening,  after  being  filled  and  inverted.  Be  careful 
not  to  raise  the  mouths  of  the  vessels  out  of  the  water  while  the 
gas  is  being  collected.  Four-ounce  wide-mouthed  bottles  are 


FIG.  3 


12  MANUAL  FOR  TEACHERS 

convenient  for  these  experiments.  Glass  squares  smeared  with 
vaseline  may  be  used  as  covers  for  these  containers ;  and  if  there 
is  not  too  much  water  left  in  the  bottles  after  the  gas  is  collected, 
several  bottles  of  gas  may  be  prepared  in  advance  and  may  be 
relied  upon  to  react  properly  when  wanted. 

Nitrogen.  To  produce  this  gas  there  are  needed  a  Florence  or 
an  Erlenmeyer  flask,  250  cc.  or  500  cc. ;  a  rubber  stopper  with 
one  opening  carrying  a  short  glass  tube  with  a  long  rubber  delivery 
tube ;  some  ammonium  chloride  (sal  ammoniac)  and  some  sodium 
nitrite,  NaNO2.  (Be  careful  not  to  use  sodium  nitrate,  NaNO3.) 
There  will  also  be  needed  a  pneumatic  trough  or  other  means 
of  collecting  gas  over  water,  bottles  with  glass  covers  smeared 
with  vaseline,  and  an  alcohol  or  Bunsen  flame.  Place  about  a  tea- 
spoonful  (level  full  or  less)  of  sal  ammoniac  and  about  an  equal 
volume  of  sodium  nitrite  in  the  flask ;  pour  in  just  enough  water 
to  cover  the  salts,  and  insert  stopper  carrying  the  delivery  tube. 
Warm  the  mixture  gently  over  the  flame,  holding  the  flask  in  the 
hand  all  the  time  so  as  to  be  able  to  regulate  the  heat  by  moving 
the  flask  nearer  to  or  farther  from  the  flame.  When  the  chemical 
action  begins,  a  great  deal  of  heat  is  generated  within  the  flask ; 
then  it  is  necessary  to  apply  only  enough  heat  from  the  outside 
to  keep  up  a  steady  action.  After  some  gas  has  escaped  from 
the  delivery  tube,  displace  the  water  in  one  or  two  bottles  to 
make  sure  that  there  is  no  more  air^in  the  generating  flask.  Then 
collect  the  gas  in  the  usual  way.  At  the  conclusion  of  the  work, 
or  when  the  generation  of  gas  is  stopped  for  any  reason,  be  care- 
ful to  take  the  delivery  tube  out  of  the  pneumatic  trough.  The 
teacher  should  try  out  the  making  of  nitrogen  before  attempting 
it  in  the  classroom. 

Oxygen.  This  gas  can  be  produced  by  hydrolysis,  if  there  is 
available  a  direct  current  of  electricity,  or  by  chemical  methods. 
For  small  quantities,  the  decomposition  of  red  oxid  of  mercury  in 
a  small  tube  by  the  application  of  heat  is  convenient.  For  making 
larger  quantities  to  be  used  in  experiments,  the  decomposition  of 
potassium  chlorate  is  the  best  method.  A  mixture  of  about  equal 
parts  of  potassium  (or  sodium)  chlorate  and  manganese  dioxid 


MANUAL  FOR  TEACHERS  13 

(both  powdered)  is  placed  in  a  large  test  tube  or  in  a  copper 
or  iron  still.  If  a  test  tube  is  used,  close  the  end  with  a  rubber 
stopper  carrying  a  delivery  tube ;  if  a  still  is  used,  connect  the 
outlet  with  a  rubber  delivery  tube.  The  mixture  of  chlorate  and 
dioxid  is  heated  steadily  (the  glass  tube  being  rotated  to  prevent 
melting  the  glass  at  one  point),  and  the  evolved  gas  is  collected 
in  the  usual  way.  Be  careful  to  remove  the  delivery  tube  from 
the  water  when  the  heat  is  withdrawn. 

To  demonstrate  the  fact  that  there  are  three  distinct  substances 
here,  notwithstanding  their  resemblance  to  each  other  and  to  the 
air,  a  bottle  of  each  gas,  labeled,  is  set  out,  and  we  proceed  to 
test  them  in  turn,  in  relation  to  burning.  A  lighted  splinter  (cigar 
lighters  are  convenient)  is  inserted  into  a  bottle  of  air  for  a  few 
moments  and  then  taken  out;  it  is  inserted  thus  in  turn  in  the 
bottle  of  nitrogen,  where  the  flame  is  instantly  extinguished.  The 
splinter  is  relighted  and  placed  in  the  carbon  dioxid,  with  the  same 
results.  It  is  finally  placed  in  the  oxygen,  where  it  instantly  blazes 
up  into  a  more  intense  flame.  Take  the  splinter  out  and  extinguish 
the  flame  by  shaking  it  or  by  blowing  it  out.  While  a  spark  still 
remains  on  the  stick  it  is  again  inserted  into  the  bottle  containing 
oxygen.  The  spark  bursts  into  flame.  There  can  be  no  doubt  left 
in  the  minds  of  the  pupils  that  it  is  the  oxygen  of  the  air  that  is 
the  significant  factor  in  burning.  Recall  the  experiment  in  which 
the  portion  of  the  air  removed  by  the  fire  was  seen  to  be  approxi- 
mately one  fifth,  and  compare  this  with  the  known  (from  authorities) 
proportion  of  oxygen. 

Oxidation.  Review  all  that  has  been  learned  about  burning,  and 
get  the  idea  of  the  products  of  combustion  being  specific  kinds 
of  compounds.  It  is  well  to  have  at  hand  specimens  of  sulfur, 
charcoal,  magnesium,  etc.,  for  demonstration  of  burning  elements. 
Get  the  generalization  about  burning  that  will  include  the  burning 
of  liquid  fuels  (alcohol,  oils,  benzine,  gasoline,  etc.),  as  well  as  of 
gaseous  fuels  (illuminating  gas,  marsh  gas,  hydrogen,  gasoline 
vapor,  etc.)  and  of  solids. 

If  there  is  time,  it  is  interesting  and  instructive  to  demonstrate 
the  burning  of  iron  with  a  flame,  and  to  compare  the  product 


14  MANUAL  FOR  TEACHERS 

with  the  rust  produced  by  weathering  of  iron  or  by  rusting  under 
water.  Ordinary  picture  cord  may  be  used,  the  strands  being  un- 
wound and  a  single  strand  at  a  time  being  employed.  Use  a  quart 
jar  full  of  oxygen,  and  ignite  by  dipping  the  looped  end  of  the  wire 
into  sulfur  (flowers)  and  igniting  the  sulfur.  •  Now  dip  this  into  the 
jar  of  oxygen,  and  the  iron  will  ignite  and  burn  with  a  visible  flame. 

"References.  In  any  available  books  on  chemistry,  general  science,  or 
the  history  of  science,  or  in  encyclopedias  and  other  books  of  reference, 
have  pupils  find  material  for  special  reports  on  such  topics  as  air,  oxygen, 
fire,  Priestley  and  oxygen,  Scheele  and  oxygen,  Lavoisier  and  oxygen, 
Cavendish  and  the  synthesis  of  water,  explosion  of  gases,  internal- 
combustion  engines,  spontaneous  combustion. 


PART  II.    LIFE  PROCESSES  OF  THE 
ORGANISM 

IV.   LIVING  THINGS  AND  NON-LIVING  THINGS 

With  the  more  direct  approach  to  living  things  as  the  object 
of  contemplation,  and  eventually  of  study,  the  students  should 
have  before  them  constantly  as  many  different  kinds  of  living 
things  as  may  be  conveniently  kept  in  the  workroom.  This  does 
not  mean  that  we  should  convert  our  laboratories  or  recitation 
rooms  into  menageries  ;  but  it  is  not  unreasonable  to  have  on 
hand  a  number  of  growing  plants,  in  pots  or  in  window  boxes,  one 
or  two  aquaria  (both  fresh  and  salt  water  if  possible),  a  vivarium 
containing  frogs,  lizards,  newts,  various  insects  according  to  season, 
slugs  and  other  animals,  and  a  hay  infusion.  In  addition  there 
should  be  exposed  prepared  specimens,  under  glass,  of  as  many 
plants  and  animals  as  the  available  cabinets  will  hold  without 
making  the  collection  a  jumble.  These  should  be  supplemented 
with  pictures  of  interesting  forms  that  cannot  otherwise  come 
within  the  common  experience  of  the  children.  Where  there  is  an 
abundance  of  material  the  teacher  will  from  time  to  time  change 
the  aspect  of  the  collection,  adding  to  the  interest  through  novelty, 
and  shifting  the  attention  as  the  need  for  emphasis  may  direct. 

As  a  preliminary  exercise  have  the  pupils  prepare  two  lists  of 
the  names  of  objects,  one  list  comprising  living  things,  the 
other,  non-living  things.  It  may  be  necessary  to  explain  that  a 
thing,  or  object,  is  not  to  be  confused  with  a  material.  For  example, 
the  earth  may  be  considered  an  object,  like  the  sun  or  the  moon  or 
a  baseball ;  but  earth  is  the  name  we  give  to  a  kind  of  stuff,  like 
iron  or  wood  or  leather.  We  often  call  an  object  by  the  name  of 
its  most  important  or  distinctive  or  sole  material,  as  when  we 
call  a  branding  tool  the  iron,  or  a  washer  the  leather,  or  a  document 

15 


1 6  MANUAL  FOR  TEACHERS 

the  paper.  The  point  of  this  exercise  is  twofold:  (i)  It  should 
help  to  clear  up  confusion  between  objects  and  classes  of  objects, 
on  the  one  hand,  and  unformed  matter  on  the  other.  (2)  It  should 
bring  clearly  into  consciousness  the  relative  paucity  of  formed 
objects  in  nature,  other  than  organisms,  and  the  practically  universal 
fact  that  life  is  related  somehow  to  formed  matter. 

It  is  well  to  have  on  view  as  many  types  of  crystals  as  can  be 
conveniently  exhibited. 

Before  the  study  of  the  text  the  pupils  should  be  encouraged 
to  analyze  their  concepts  of  living  things  by  listing  all  the 
characteristics  of  organisms  that  they  can  think  of.  These  lists 
may  then  be  used  as  a  basis  of  criticism  and  discussion. 

In  the  discussion  of  differences  or  similarities  between  living 
and  non-living,  the  pupils  should  be  encouraged  to  formulate  their 
concepts  in  good  sentences ;  and  they  should  be  encouraged  then 
to  modify  their  generalizations  by  expanding  their  observations  to 
types  that  do  not  appear  to  agree  with  these  concepts.  Reference 
to  the  plants  (that  do  not  walk  about),  to  the  worms  (that  have  no 
stomachs  or  brains),  to  the  organisms  without  blood,,  etc.,  are 
largely  in  the  nature  of  challenges,  and  pains  must  be  taken  to 
avoid  driving  the  pupils  to  desperation.  But  it  is  possible  gradu- 
ally to  get  them  to  see  that  life  is  not  to  be  comprised  in  a  word 
or  in  a  single  differential. 

About  a  week  before  the  class  is  ready  to  consider  growth, 
arrange  a  demonstration  of  inorganic  growth  as  follows : 

In  the  bottom  of  a  battery  jar  or  large  fruit  jar  place  a  layer 
of  clean  sand.  On  the  sand  place  a  number  of  crystals,  as  of 
copper  sulfate,  ferrous  sulfate,  chrome  alum,  zinc  sulfate,  etc. 
Pour  slowly  into  the  jar  a  mixture  of  sodium  silicate  (water 
glass)  and  water,  about  one  part  to  fen.  The  prepared  jar  is  to 
stand  undisturbed  where  it  may  be  observed  without  being  moved. 

Saturated  solutions  of  sugar,  alum,  and  other  substances  that 
crystallize  readily  may  be  prepared,  and  the  growth  of  crystals 
watched.  By  suspending  a  thread  (weighted)  in  such  a  solution, 
the  crystallization  may  be  started,  and  the  growth  of  the  mass 
about  the  string  as  an  axis  may  be  watched.  Compare  rock 


MANUAL  FOR  TEACHERS  I/ 

candy.  It  may  be  feasible  to  have  the  children  prepare  such 
growths  at  home. 

Compare  the  assimilation  of  foreign  peoples,  or  of  new 
pupils  in  a  school. 

If  there  is  not  common  familiarity  with  photographic  materials 
and  processes,  demonstrate  the  modification  of  blue-print  paper  or 
printing-out  paper  under  the  influence  of  light. 

In  the  study  of  functions  the  idea  can  be  made  more  clear 
by  emphasizing  the  fact  that  we  think  of  use  chiefly  in  terms 
of  human  advantage,  and  then  contrasting  function  with  use.  For 
this  exercise,  have  each  student  prepare  two  sheets  of  paper  (or 
pages  of  the  notebook)  by  dividing  the  space  into  four  columns, 
headed  as  below : 


NAME  OF  ORGANISM 

PART  USED 

How  USED 

FUNCTION 

One  sheet  is  to  be  used  for  plants,  the  other  for  animals. 
A  few  illustrations  will  appear  in  the  course  of  the  discussion ; 
these  may  be  used  to  start  the  lists,  and  each  pupil  may  then  be 
required  to  bring  say  ten  or  a  dozen  on  each  list.  The  most  com- 
monly used  parts  of  the  more  familiar  plants  and  animals  will  serve 
as  the  most  striking  means  for  emphasizing  the  contrast  between 
use  2X\&.  function,  —  for  example,  the  tongue  of  the  cow,  the  tail  of 
the  ox,  the  root  of  the  carrot,  the  bark  of  the  hemlock,  etc. 

Be  careful  at  this  point,  as  always,  to  keep  clear  of  the  pre- 
conceived notions  of  purpose.  It  can  easily  be  made  plain  to  even 
the  least  mature  pupils  that  the  function  of  a  given  organ  is  by  no 
means  an  indication  of  purpose  on  the  part  of  the  organism.  You 
have  but  to  ask,  "  For  what  purpose  did  you  grow  yourself  a 
liver  ? "  or  "  What  was  your  purpose  in  building  four  chambers 
into  your  heart  ? "  —  and  the  child  sees  at  once  that  he  grew  up 
without  purpose  on  his  own  part ;  and  this  repudiation  of  purpose 
may  be  extended  to  other  organisms.  It  remains  then  a  question 


1 8  MANUAL  FOR  TEACHERS 

of  Nature's  purpose  or  God's  purpose,  which  imply  assumptions 
that  we  do  not  need  for  our  purpose,  or  which  imply  interpreta- 
tions that  are  of  no  use  to  us.  At  any  rate,  purpose  must  not  be 
allowed  to  interfere  with  the  purposes  of  our  study. 

References.  HUXLEY,  T.  H.,  On  the  Physical  Basis  of  Life,  in  his 
"  Methods  and  Results,"  Essay  3 ;  JORDAN  and  KELLOGG,  Evolution  and 
Animal  Life,  chap,  iii ;  LOCY,  W.  A.,  Biology  and  its  Makers,  chap,  xii ; 
LOEB,  JACQUES,  The  Organism  as  a  whole,  chap,  ii ;  MORGAN,  T.  H.,  Evo- 
lution and  Adaptation,  chap,  i;  WILSON,  E.  B.,  The  Cell,  pp.  17-30. 
The  abler  pupils  can  read  the  first  two  of  the  above ;  have  all  look  up  in 
available  books  on  botany  and  zoology  such  topics  as  protoplasm  and  cell. 

V.   THE  LIVING  STUFF 

In  comparing  plants  and  animals,  have  living  specimens  within 
sight  and  within  reach.  See  suggestions  under  IV. 

Hay  infusions  prepared  for  protozoa  usually  die  out  in  a 
short  time.  To  keep  a  supply  on  hand  use  this  method :  Prepare 
a  culture  medium  by  boiling  hay  in  water,  with  a  little  corn  meal, 
until  the  liquor  is  of  a  dark  brown  color.  Leave  a  small  amount 
of  the  hay  in  the  liquor.  This  may  be  kept  indefinitely  in  sealed 
bottles.  For  use,  expose  some  hay  infusion  in  a  battery  jar  for  a 
day  or  two,  in  order  to  inoculate  with  bacteria  from  the  air.  Cover 
with  a  glass  plate  and  leave  until  a  scum  appears.  Then  add  some 
water,  mud,  etc.  from  a  pond  or  ditch.  Several  jars  may  be  pre- 
pared, and  inoculated  with  material  from  different  sources.  In  a 
few  days  the  protozoa  will  be  sufficiently  abundant;  the  supply 
should  last  for  several  months.  It  is  well  to  inoculate  a  fresh 
hay  infusion  every  three  or  four  months,  using  some  of  the  old 
culture  for  this  purpose. 

Leaves  of  Elodea,  myriophyllum,  or  other  delicate  water  plants, 
filaments  of  spirogyra  or  other  algae,  epidermal  cells  of  almost  any 
kind  of  leaf,  or  onion  skin,  will  give  sufficient  material  for  forming 
the  idea  of  cells  as  structural  units,  as  well  as  something  of  the 
nucleus,  vacuoles,  and  non-living  bodies  within  the  cell.  Animal  cells 
are  better  shown  from  prepared  slides.  Call  attention  to  the  fact 
that  the  colors  in  such  specimens  are  due  to  the  artificial  stains 
used  for  the  purpose  of  making  the  structural  details  visible. 


MANUAL  FOR  TEACHERS  19 

It  may  be  worth  while  to  give  the  pupils  some  instruction  in  the 
use  of  the  microscope.  To  familiarize  students  with  the  inversion 
of  the  image,  it  has  been  found  helpful  to  prepare  a  set  of  slides 
by  mounting  permanently  in  balsam  tiny  bits  of  paper  cut  from 
some  printed  matter  (small  type,  one  side  of  paper  only),  each 
containing  two  or  three  letters.  These  slides  are  studied  with  the 
naked  eye,  with  the  simple  microscope,  and  with  the.  low  power 
of  the  compound  microscope.  The  making  of  drawings  of  the 
object  under  these  three  conditions,  with  the  slide  always  kept 
in  the  same  position  in  front  of  the  student,  will  accelerate  the 
formation  of  the  ideas  needed  in  the  control  of  the  instrument. 

In  most  cases  it  will  suffice  to  set  up  the  microscopes  with  the 
demonstration  material  already  centered  and  focused,  and  have 
the  students  look  at  the  preparations. 

Chromosomes,  if  they  are  to-be  seen,  must  not  be  searched  for 
in  fresh  preparations.  If  desired,  prepared  slides  may  be  made 
or  purchased,  —  as,  for  example,  root-tips  of  onion. 

If  it  is  not  feasible  to  place  protozoa  and  living  tissues  under 
the  observation  of  the  students,  for  the  purpose  of  forming  a 
definite  idea  of  the  appearance  of  protoplasm,  it  is  often  worth 
while  to  prepare  an  emulsion  of  oil  and  salt  water.  This  emulsion 
exhibits  constant  movements  of  a  kind  that  are  in  some  ways 
similar  to  those  seen  in  living  protoplasm ;  and  while  the  students 
may  not  know  anything  of  surface  tension,  they  do  know  that 
"  oil  and  water  will  not  mix,"  a"nd  that  the  movements  in  the 
emulsion  are  due  to  the  "unmixing"  of  the  oil  and  water. 

References.  LOCY,  \V.  A.,  Biology  and  its  Makers,  chap,  xi;  LOEB,  JACQUES, 
The  Dynamics  of  Living  Matter,  chap,  iii ;  WILSON,  The  Cell,  chap.  i. 

VI.    THE  CONDITIONS  OF  LIFE 

Before  beginning  the  study  of  the  relation  between  the  environ- 
mental factors  and  life  processes,  it  is  well  to  make  an  inventory  of 
what  the  members  of  the  class  already  know  on  the  subject.  We 
shall  find  many  beliefs  that  are  unsupported,  many  that  will  not 
stand  critical  examination.  On  the  other  hand,  it  is  not  worth  while 
to  demonstrate  anew  what  is  already  well  established  for  all  of  us. 


2O  MANUAL  FOR  TEACHERS 

By  contrasting  the  conditions  that  obtain  in  a  jar  containing 
seeds  that  do  not  sprout,  with  the  conditions  in  the  ground,  where 
seeds  do  sprout,  we  are  enabled  to  analyze  the  environment  for 
the  purpose  of  selecting  the  significant  factors,  or  for  the  purpose 
of  formulating  hypotheses  that  can  be  subjected  to  experimental 
test.  The  fact  that  seeds  behave  in  one  way  in  the  storage  bin 
and  in  quite  a  different  way  in  the  soil  furnishes  the  occasion  and 
the  opportunity  for  seeking  in  the  sprouting  conditions  of  seeds 
the  answer  to  our  general  question. 

Have  a  list  of  all  the  suggested  factors  made  on  the  board ; 
check  out  those  that  are  the  same  for  seeds  in  storage  and  seeds 
in  the  soil.  There  will  be  left  for  immediate  experiment  hardly 
anything  more  than  water;  for  although  other  factors  may  be 
related  to  the  sprouting,  they  appear  to  be  the  same  for  the  resting 
seeds  and  for  the  developing  embryos.  Before  proceeding  with 
any  experiments,  therefore,  it  is  well  to  emphasize  the  idea  that, 
while  we  are  seeking  for  single  determining  factors,  we  must  be 
prepared  to  consider  the  possibility  of  a  determining  combination 
of  factors. 

Have  students  formulate  the  general  problem,  What  is  the 
relation  of  this  facto?'  to  the  sprouting  of  seeds  ?  Then  have  a 
plan  of  campaign  worked  out  by  the  class.  When  a  satisfactory 
plan  is  agreed  upon,  have  committees  of  the  students  arrange  a 
demonstration  series  for  the  class ;  those  who  are  in  a  position 
to  do  so  should  be  encouraged  to  perform  special  experiments 
at  home. 

A  satisfactory  plan  must  include  the  control.  This  should  appear 
in  the  course  of  the  discussion ;  the  teacher  should  avoid  present- 
ing the  idea  as  authoritative  or  as  standard  practice. 

Whatever  plan  is  used  for  determining  the  relation  of  moisture 
to  sprouting,  occasion  should  be  found  or  made  for  introducing 
the  problem  of  quantity,  —  Does  an  increase  in  moisture  acceler- 
ate the  process  ?  This  should  offer  opportunity  for  experimental 
demonstration  leading  to  the  idea  of  the  optimum. 

Have  reports  of  the  experiments  made  out  in  good  form  (see 
p.  8),  and  so  far  as  possible  have  data  presented  in  tables.  For 


MANUAL  FOR  TEACHERS  21 

example,  the  conditions  and  results  of  the  experiment  can  be  pre- 
sented in  tabular  form,  or  the  results  on  successive  days  may  be 
tabulated. 

After  the  students  have  formulated  their  conclusions  as  to  the 
relation  of  moisture  to  sprouting,  it  is  in  order  to  take  up  some 
of  the  factors  that  have  been  laid  aside  as  being  the  same  in  the 
two  contrasted  situations.  For  example,  What  is  the  relation  of 
air,  of  temperature,  of  light,  to  sprouting? 

As  before,  have  the  problems  and  the  plans  formulated  by  the 
students,  giving  suggestions  only  where  necessary,  yet  not  unduly 
prolonging  the  preliminaries. 

Differential  air  conditions  may  be  obtained  by  using  vessels  of 
different  sizes  for  a  given  number  of  seeds  or  by  placing  different 
numbers  of  seeds  in  a  series  of  vessels  of  the  same  size.  Of 
course  the  seeds  are  to  be  soaked  in  water  in  advance,  since  we 
know  that  moisture  is  essential.  Another  method  would  be  to 
exclude  different  amounts  of  air  from  bottles  of  the  same  size, 
by  means  of  soil  or  plaster  of  Paris.  A  practical  vacuum  may  be 
obtained  by  inverting  a  test  tube  full  of  mercury  into  a  mercury 
bath  (avoiding  the  entrance  of  air  bubbles),  and  then  carefully 
slipping  in  a  few  soaked  peas.  The  tube  may  be  held  in  place 
with  a  clamp  on  a  ring  stand. 

For  differences  in  temperature  use  a  refrigerator,  the  classroom 
and  the  boiler  room,  or  a  place  close  to  the  radiator  or  stove. 
The  difficulty  of  obtaining  constant  temperatures  of  three  or  four 
grades  would  usually  preclude  this  experiment  Where  ovens  or 
incubators  with  thermostats  are  available,  the  experiment  is  well 
worth  performing. 

Problems  as  to  light  and  other  factors  may  well  be  left  to  the 
initiative  and  ingenuity  of  individual  pupils  who  are  especially 
interested.  It  is  well  to  have  the  experiments  performed  according 
to  different  methods,  and  to  have  the  results  compared  and  dis- 
cussed in  class.  For  example,  in  the  experiment  on  the  relation 
of  moisture  to  sprouting,  some  may  use  soil,  others  sand,  or  saw- 
dust, or  blotting  paper,  and  so  on ;  while  in  one  series  the  glass 
vessels,  the  water,  and  the  seeds  are  used  without  any  matrix. 


22 


MANUAL  FOR  TEACHERS 


References.  ANDREWS,  E.  F.,  Practical  Course  in  Botany,  pp.  10-12, 
30-40,  chap,  vii;  BERGEN  and  CALDWELL,  Practical  Botany,  pp.  139-141; 
BERGEN  and  DAVIS,  Principles  of  Botany,  chap,  i;  COULTER,  J.  M.,  Ele- 
mentary Studies  in  Botany,  pp.  174-176;  DUGGAR,  B.  M.,  Plant  Physiology, 
pp.  280-296,  chap,  xv ;  MORGAN,  T.  H.,  Experimental  Zoology,  chap,  i ; 
OSTERHOUT,  W.  J.  V.,  Experiments  with  Plants,  chap.  i.  Morgan  is  for  the 
teacher  only ;  in  the  others  will  be  found  many  suggestions  for  individual 
experiments  and  projects  for  pupils. 

VII.   AIR  AND  SOIL  IN  RELATION  TO  SPROUTING 

To  show  which  of  the  gases  in  the  air  is  related  to  sprouting, 
prepare  flasks  of  carbon  dioxid,  of  nitrogen,  and  of  oxygen,  with 
seeds  that  have  been  soaked  in  water. 
The  control  consists  of  a  flask  of  the 
same  size,  containing  the  same  number 
of  seeds  but  ordinary  air  instead  of  any 
special  gas.  All  the  flasks  are  sealed 
with  paraffin,  and  they  are  kept  together 
for  the  sake  of  the  uniform  temperature 
and  light.  It  is  well  to  wash  the  gases 
used  in  this  experiment  by  passing 
through  clean  water  in  a  bottle  con- 
nected as  shown  in  Fig.  4. 

We  can  test  the  gases  left  in  the  flasks 
wherein  the  seeds  sprouted,  for  an  in- 
crease in  the  amount  of  carbon  dioxid. 
To  show  that  the  sprouting  seeds  give 
off  heat,  fill  two  large  bottles  with  seeds 
that  have  been  soaked  for  twenty-four 
hours ;  to  the  contents  of  one  of  the 
vessels  add  a  little  formalin,  to  kill  the 
seeds  without  altering  their  appearance.  In  each  bottle  insert  a 
thermometer;  and  if  a  third  thermometer  is  available,  have  that 
in  the  air  beside  the  bottles.  Place  the  two  bottles  together  in 
a  suitable  box  and  pack  in  with  cotton  waste,  sawdust,  or  other 
material,  to  prevent  rapid  change  of  temperature.  Read  the  ther- 
mometers from  time  to  time  and  have  the  results  tabulated.  Under 


FIG.  4 


MANUAL  FOR  TEACHERS 


favorable  conditions  there  should  be  a  difference  of  several  degrees 
(centigrade)  between  the  temperature  of  the  sprouting  seeds  and 
that  of  the  soaked  seeds  that  did  not  sprout,  or  the  surrounding  air. 

Compare  the  sprouting  seeds  to  other  living  things  and  to  engines. 

The  suggestion 
that  animals  and 
human  beings  re- 
semble the  germi- 
nating seeds  in  that 
they  give  off  heat 
and  use  up  oxy- 
gen can  be  carried 
farther  by  testing 
at  the  same  time 
the  exhaled  air  and 
the  ordinary  room 
air  in  their  effect 
upon  limewater. 
The  set  of  bottles 
shown  in  Fig.  5 
will  facilitate  the 
demonstration. 

Have  the  idea 
of  soil  analyzed  in- 
to sand  and  other 
insoluble  constit- 
uents, salts,  and 
organic  remains. 
Since  the  salts  ap- 
pear to  be  the 

factors  most  likely  to  influence  the  plants,  the  experiments  would 
center  about  them.  After  formulating  the  problems  and  making 
the  plans,  arrange  to  grow  seedlings  in  clean  sand  moistened 
with  pure  water ;  that  is,  water  free  from  dissolved  matter. 
Use  distilled  water  and  explain  how  the  purity  of  this  differs 
from  the  purity  of  pure  drinking  water.  As  a  control,  make  a 


FIG.  5 

When  the  free  end  of  the  Y-tube  is  used  as  a  mouthpiece, 
inhalation  of  air  draws  the  gas  through  one  of  the  bottles, 
and  exhalation  drives  the  gas  through  the  other  bottle. 
Limewater  placed  in  both  bottles  will  show  the  difference 
between  inhaled  air  and  exhaled  air  very  strikingly 


24  MANUAL  FOR  TEACHERS 

parallel  growth  in  garden  soil,  and  another  in  clean  sand  moistened 
with  tap  water,  well  water,  or  the  like,  or  a  special  solution  known 
to  contain  salts.1  A  comparison  of  the  condition  of  the  plants  after 
a  prolonged  growth,  or  at  the  time  when  some  begin  to  show  evi- 
dence of  deterioration,  will  throw  light  on  the  relation  of  soil  salts 
to  the  life  of  the  plant. 

The  nutritive  solution  may  be  used  either  as  root  medium  (in 
contrast  with  distilled  water)  or  for  watering  the  sand.  In  the 
latter  case  it  may  be  diluted  with  an  equal  volume  of  distilled 
water. 

In  the  case  of  every  experiment  the  students  should  be  called 
upon  to  formulate  the  problems  and  to  indicate  at  least  the  gen- 
eral form  of  the  experimental  procedure.  The  results  should  be 
tabulated  so  far  as  possible. 

It  is  impossible,  for  a  considerable  time,  to  draw  conclusions  from 
the  experiments  suggested  for  this  chapter ;  it  is  therefore  well, 
immediately  after  setting  up  the  experiments,  to  undertake  further 
studies  on  the  structure  of  seeds,  coming  back  to  conclusions  and 
summary  later. 

References.  ANDREWS,  Practical  Course  in  Botany,  pp.  30-40;  BERGEN 
and  CALDWELL,  Practical  Botany,  pp.  447-448;  COULTER,  Elementary 
Studies,  Part  II,  chaps,  ii,  iii ;  DUGGAR,  Plant  Physiology,  chaps,  vii,  viii. 

1  A  culture  medium  for  growing  plants  without  soil  may  be  prepared 
by  dissolving  in  each  liter  of  distilled  water 

Potassium  nitrate i.o  gram 

Calcium  sulfate 0.5  gram 

Calcium  phosphate 0.5  gram 

Magnesium  sulfate 0.5  gram 

Sodium  chlorid 0.5  gram 

Ferric  chlorid,  or  ferrous  sulfate  solution A  few  drops 

Another  formula  for  a  nutritive  solution  is  the  following :  To  each  liter 
of  distilled  water  add 

Calcium  nitrate i.oogram 

Magnesium  sulfate 0.25  gram 

Potassium  chlorid 0.25  gram 

Monopotassium  phosphate 0.25  gram 

Iron  solution A  few  drops 


v  MANUAL  FOR  TEACHERS  25 

VIII.   SEEDS  AND  SEEDLINGS 

For  the  study  of  seed  structure,  kidney  beans,  pumpkin  or 
squash  seeds,  large  peas,  and  corn  will  furnish  convenient  illus- 
trative material.  Seeds  to  be  taken  apart  should  be  soaked  at 
least  twenty-four  hours;  a  few  drops  of  formalin  in  each  jar 
containing  soaked  seeds  will  prevent  decomposition. 

For  the  study  of  the  main  parts  of  a  plant,  any  small  weeds 
that  can  be  pulled  up  by  the  roots  and  gathered  in  quantities  may 
be  used. 

In  making  drawings  of  structures  studied,  we  should  avoid, 
on  the  one  hand,  hasty  and  careless  sketches  that  do  not  really 
show  the  significant  features,  and,  on  the  other  hand,  elaborate 
and  artistic  drawings  that  show  too  much,  often  concealing  the 
significant  features  amid  a  mass  of  unessential  detail.  To  make 
large,  clear,  diagrammatic  figures  that  show  forms  and  relation- 
ships is  a  trick  worth  cultivating.  It  is  worth  while  to  suggest 
convenient  methods  of  arranging  and  labeling  drawings,  as  well 
as  suitable  lettering  and  location  for  names,  dates,  class  designa- 
tions, etc.  But  it  is  easy  to  lose  a  great  deal  of  time  in  elaborat- 
ing on  these  details,  and  a  great  deal  of  energy  in  insisting  upon 
uniformities  that  are  in  the  end  unimportant. 

Where  the  students  take  an  interest  in  classification  it  may  be 
suggested  that  a  committee  prepare  a  chart  with  three  columns, 
on  which  are  to  be  entered  the  names  of  plants  as  they  come  to 
the  attention  of  the  class,  according  to  the  number  of  cotyledons 
in  the  seeds.  This  device  will  tend  to  place  the  more  familiar  seed 
plants  in  their  main  divisions,  and  will  also  help  to  fix  the  idea  that 
there  are  many  plants  that  never  bear  seeds. 

Collections  of  economic  seeds  should  be  encouraged,  and  some 
should  be  made  for  the  school  museum. 

The  experiments  on  the  relation  of  the  accumulated  food  in  the 
seed  to  the  life  of  the  young  plant  are  easily  performed  by  the 
students  themselves  or  may  be  done  in  the  laboratory  for  demon- 
stration. After  sprouting  soaked  corn  grains,  the  bulk  of  the 
endosperm  is  cut  away  and  the  hypocotyl  is  passed  through  a 


26 


MANUAL  FOR  TEACHERS 


small  hole  in  a  piece  of  cheesecloth  or  muslin  stretched  over  the 
top  of  a  bottle  or  tumbler  rilled  with  water.  Pea  seedlings  with 
the  cotyledons  removed  are  arranged  in  a  similar  way.  The  con- 
trol consists  of  the  seedlings  with  the  endosperm  or  cotyledons 
undisturbed.  Fig.  6  shows  the  results  of  such  experiments. 


Corn 
seedlings 


FIG.  6 


To  discover  whether  there  has  been  any  loss  of  material  from 
the  cotyledons  of  the  growing  plantlets,  dig  up  seedlings  that  have 
been  grown  in  sand  or  soil,  and  compare  with  the  cotyledons  of 
fresh-soaked  seeds.  . 

Seedlings  should  be  started  in  flat  boxes  of  soil  or  sand  (or 
sawdust)  at  intervals  of  two  days  for  two  or  three  weeks  before 
they  are  to  be  used.  They  will  serve  for  comparative  study  of 
structure  and  of  emergence. 


MANUAL  FOR  TEACHERS  2/ 

References.  ANDREWS,  Practical  Course,  pp.  40-47  ;  BERGEN  and  CALD- 
WELL,  Practical  Botany,  pp.  136-144;  BERGEN  and  DAVIS,  Principles  of 
Botany,  chap,  iii ;  COULTER,  J.  G.,  Plant  Life  and  its  Uses,  pp.  348-353; 
COULTER,  J.  M.,  Elementary  Studies,  Part  II,  chap,  iv  ;  COULTER,  BARNES, 
and  COWLES,  Textbook  of  Botany,  pp.  270-275  (for  the  teacher) ;  OSTER- 
HOUT,  Experiments  with  Plants,  chap.  i. 


IX.  EXTERNAL  FORCES  AND  PLANTS 

The  demonstration  of  geotropism  with  the  aid  of  the  centrifuge  or 
the  clinostat  is  not  satisfactory  for  high-school  students  who  have  not 
yet  studied  physics,  since  it  involves  the  identification  of  centrifugal 
acceleration  with  gravity.  To  get  this  clearly  requires  too  much  digres- 
sion. It  is  better  to  use  an  arrangement  that  permits  the  inversion  of 
the  seedlings  from  time  to  time. 

A  convenient  arrangement  for  the  study  of  geotropism  consists 
of  two  panes  of  glass  (any  size  will  do),  one  serving  as  a  base  and 
the  other  as  a  cover.  The  bottom  glass  is  covered  with  cotton 
wool  or  wrinkled  filter  paper,  upon  which  soaked  seeds  are  placed. 
In  placing  the  cover  on  top  of  the  seeds,  it  is  well  to  insert  bits 
of  cork  under  the  corners,  to  prevent  crushing  the  seeds.  The 
two  panes  are  held  together  by  means  of  rubber  bands.  The  wet 
cotton  or  paper  extends  beyond  the  end  of  the  glass.  The  whole 
arrangement  is  set  up  vertically  in  a  shallow  dish  containing  a 
little  water  in  the  bottom.  The  cotton  or  paper  protruding  beyond 
the  top  of  the  glass  is  turned  back  into  the  water.  In  this  way 
the  absorption  of  water  to  keep  the  seeds  moist  is  not  altogether 
from  below.  After  the  seeds  have  sprouted,  the  position  of  the 
hypocotyls  is  noted,  and  every  day  or  two  the  glasses  are 
turned  over. 

Students  can  be  interested  in  carrying  out  this  experiment  at 
home.  If  there  are  not  enough  suitable  pieces  of  glass  available, 
the  bottom  can  be  made  of  a  piece  of  thin  wood.  By  using  small 
seeds  (radish,  flax,  or  mustard)  and  blotting  paper,  enough 
moisture  can  be  supplied  without  extending  the  absorbing  material 
beyond  the  edge  of  the  glass.  The  edges  may  then  be  loosely 
inclosed  with  dry  paper,  to  prevent  excessive  evaporation. 


28 


MANUAL  FOR  TEACHERS 


If  the  material  is  kept  in  condition  long  enough,  the  negative 
geotropism  of  the  shoots  can  also  be  demonstrated.  In  making 
experiments  with  the  geotropism  in  shoots  of  older  plants,  be 
careful  to  avoid  one-sided  illumination. 

In  the  experiment  on  the  geotropism  of  the  root,  it  should  not 
be  difficult  to  make  the  class  see  that  downward  growth  is  some- 
thing different  from  falling  down ;  occasionally,  however,  a  student 
becomes  confused  on  this  point.  In  such  a  situation  the  fact  that 

the  pressure  of  the  root  down- 
ward is  far  in  excess  of  the 
weight  of  the  plant  may  be 
conveniently  shown  by  mak- 
ing a  hypocotyl  penetrate 
into  mercury.  Windsor  beans 
are  convenient  for  this  ex- 


^^J^^^IJI  periment,  and  the  sprouted 
seed  is  pinned  to  a  cork  fast- 
ened over  the  dish  of  mer- 
cury, with  a  little  water  over 
it,  as  shown  in  Fig.  7. 
FIG.  7  An  ingenious  device  for  actu- 

ally measuring  the  downward 

pressure  of  a  root  is  described  in  Osterhout's  "  Experiments 
with  Plants,"  pp.  81-85.  See  also  Ganong's  "  Plant  Physiology." 
To  demonstrate  the  growth  movements  in  roots,  use  peas  that 
have  been  allowed  to  sprout  in  moist  paper,  having  fairly  straight 
hypocotyls  about  an  inch  long.  Mark  off  intervals  of  about  i  mm. 
from  the  tip  of  the  root,  using  india  ink  and  a  scale.  For  apply- 
ing the  ink  use  a  very  fine  pen  or  a  bow  made  of  a  horsehair  or  a 
fine  silk  thread  stretched  between  the  ends  of  a  piece  of  spring 
steel.  Replace  the  young  plants  among  the  folds  of  moist  paper, 
with  the  tips  in  a  horizontal  position  but  free  to  bend  down.  The 
results  after  a  day  or  two  will  show  not  only  the  region  of  maxi- 
mum growth  in  the  tip  of  the  root,  but  also  the  fact  that  the  curva- 
ture is  brought  about  by  more  rapid  growth  on  one  side  than  on 
the  opposite  side. 


MANUAL  FOR  TEACHERS  29 

The  response  of  plants  to  light  stimulation  may  be  shown  by 
comparing  plants  grown  in  different  degrees  of  illumination,  or 
by  watching  the  behavior  of  plants  exposed  to  one-sided  illumina- 
tion. For  the  first  experiment  divide  a  lot  of  seedlings  of  about 
the  same  stage  of  development  into  two  sets.  Cover  one  set  with 
a  pasteboard  box  that  will  effectually  exclude  the  light  without 
excluding  adequate  ventilation.  In  the  course  of  a  few  days  it  will 
be  possible  to  see  differences  in  the  height  of  the  two  groups:  In 
a  few  days  more  it  will  be  possible  to  observe  the  blanching  of 
the  plants  deprived  of  light.  It  is  fair  to  conclude  from  these 
results  that  light  retards  the  growth  of  plants,  and  that  the  green 
of  the  plant  can  be  maintained  only  in  the  presence  of  light. 
Emphasize  the  fact  that  darkness  is  a  negative  condition ;  it 
is  not  darkness  that  makes  plants  grow  faster,  but  light  that 
retards  the  growth. 

Plants  grown  in  flowerpots  inside  the  window  will  frequently 
present  the  effect  of  one-sided  illumination,  in  that  the  leaves  will 
be  turned  with  the  flat  surface  parallel  to  the  window  or  with  the 
tips  inclined  toward  the  window.  Geraniums  are  very  good  for 
this.  To  show  that  the  position  of  the  leaf  is  not  a  random  one, 
the  pots  should  be  turned  through  an  arc  of  180  degrees  and  the 
positions  marked,  on  successive  days.  Have  students  look  up 
"  compass  plants  "  and  bring  in  evidences  of  phototropism  from 
field  and  garden  or  from  house  plants. 

It  is  not  worth  while  to  demonstrate  chemotropism,  although 
any  students  who  are  sufficiently  interested  to  do  so  should  be 
encouraged  to  work  out  plans  and  carry  out  experiments  by 
themselves,  and  report  to  the  class.  . 

Hydro tropism  is  easily  demonstrated.  Fill  a  small  flowerpot  or 
a  Zurich  germinator  with  sphagnum,  kept  moist.  On  the  outside 
of  the  pot  place  some  mustard  seeds,  which  will  adhere  because 
of  a  mucilaginous  substance  they  secrete.  Suspend  the  pot  under 
a  bell  jar  or  a  large  battery  jar.  The  roots,  instead  of  growing 
down,  will  cling  to  the  moist  surface  of  the  pot.  The  control  con- 
sists of  an  identical  arrangement  in  a  jar  containing  a  vessel  of 
water,  to  keep  the  atmosphere  saturated ;  in  this  jar  the  roots 


30  MANUAL  FOR  TEACHERS 

will  grow  downward.  Another  arrangement  consists  of  a  wire 
basket  filled  with  wet  sphagnum  or  excelsior,  in  which  the  seeds 
germinate.  After  the  roots  have  projected  beyond  the  basket, 
suspend  the  latter  with  the  bottom  inclined,  so  that  the  nearest 
water  for  each  root  is  not  down  but  to  one  side.  This  should 
be  placed  under  a  jar,  to  prevent  drying  of  the  roots. 

References.  For  the  teacher:  COULTER,  BARNES,  and  COWLES,  Text- 
book, pp.  458-479;  DARWIN,  CHARLES,  Movement  in  Plants;  LOEB, 
Dynamics  of  Living  Matter,  Lect.  VII,  VIII.  For  the  pupils :  ANDREWS, 
Practical  Course,  pp.  47-52;  COULTER,  Plant  Life,  pp.  131-134;  DUGGAR, 
Plant  Physiology,  chap,  xx,  pp.  415-420;  OSTERHOUT,  Experiments,  chap.  ii. 

X.   ABSORPTION  FROM  THE  ENVIRONMENT 

To'  introduce  the  subject  of  osmosis,  it  is  well  to  begin  with 
practical  demonstrations  of  diffusion.  Open  a  bottle  containing 
acetic  acid,  ether,  chloroform,  alcohol,  formalin,  or  some  other 
substance  with  a  decided  odor.  Open  the  gas  cock  for  a  few 
moments.  When  it  is  evident  that  the  odorous  substance  has 
reached  some  distance  from  its  source,  the  subject  of  diffusion 
may  be  taken  up. 

For  diffusion  in  liquids,  prepare  some  bottles  or  tumblers  of 
water  and  place  in  each  a  lump  of  sugar  or  salt.  Into  a  beaker  or 
jar  of  water  that  has  been  standing  for  some  time,  so  that  there 
are  no  movements  or  currents  in  it,  let  fall  a  drop  of  red  ink 
(eosin  solution  or  some  other  water-soluble  pigment  will  do).  The 
diffusion  of  the  salt  or  sugar,  and  that  of  the  ink,  are  visible  and 
demonstrate  the  action  of  some  form  of  attraction  that,  in  the  one 
case,  raises  the  material  from  the  bottom  of  the  jar  to  the  surface 
of  the  water  (since  in  time  the  diffusion  will  result  in  an  equal 
distribution  of  the  material  throughout  the  liquid),  and  in  the  other 
case  spreads  it  through  a  quiet  body  of  water. 

To  illustrate  absorption  without  diffusion,  sheets  of  glue  or  of 
gelatin  may  be  used.  Wood,  leather,  and  paper  behave  in  much 
the  same  way,  except  that  the  glue  and  gelatin  are  practically 
homogeneous  substances,  whereas  the  other  materials  represent 
structures  with  visible  (microscopic)  pores. 


MANUAL  FOR  TEACHERS  31 

An  artificial  root  hair  or  cell  may  be  made  of  goldbeater's 
skin  or  of  celloidin.  The  latter  is  to  be  preferred  because  it 
gives  a  homogeneous  membrane  that  the  students  can  see  in  the 
course  of  formation.  Use  a  pure  celloidin  dissolved  in  alcohol  and 
ether,  free  from  acetone.  Pour  a  little  of  the  celloidin  into  a  clean, 
dry  bottle  (4-oz.  wide-mouthed)  and  then  slowly  pour  out  what  you . 
can  (back  into  the  original  container),  turning  the  bottle  all  the 
while  so  as  to  spread  the  celloidin  evenly  over  the  inner  surface 
of  the  bottle.  Allow  to  stand  for  several  minutes,  blowing  into 
the  bottle  from  time  to  time,  to  accelerate  the  evaporation  of  the 
ether  and  alcohol.  Prepare  for  each  bag  a  two-hole  rubber  stopper 
(size  No.  4  or  No.  5),  a  thistle  tube,  a  rubber  band,  and  a  glass 
plug  to  fit  into  one  of  the  holes  in  the  stopper.  There  will  also 
be  needed  a  mixture  of  sirup  or  molasses  and  water,  a  jar  of  clean 
water,  and  a  support 

After  all  of  the  ether  has  evaporated  from  the  "  newskin " 
membrane  in  the  bottle  (as  you  can  tell  by  the  odor),  add  a  little 
water,  which  will  accelerate  the  removal  of-  the  alcohol.  With  a 
little  careful  manipulation  it  is  possible  to  remove  the  bag  from 
the  bottle  without  breaking  it.  Insert  the  rubber  stopper  in  the 
neck  of  the  bag,  and  make  fast  with  a  few  turns  of  the  rubber 
band.  Insert  the  thistle  tube,  and  the  bag  is  ready  to  be  filled 
with  the  sirup.  After  a  little  practice  the  teacher  should  be  able 
to  make  the  bag  in  a  few  minutes,  and  thus  to  complete  the  whole 
operation  in  the  presence  of  the  class. 

After  pouring  in  the  sirup  until  the  bag  is  quite  full,  plug  the 
vent,  wash  off  the  outside,  and  place  in  the  jar  of  clean  water, 
suspending  the  cell  so  that  it  does  not  come  in  contact  with  the 
sides  of  the  jar.  Note  the  height  of  the  liquid  on  the  inside,  and 
watch  the  rise  of  liquid  in  the  thistle  tube.  If  it  is  desired  to  con- 
tinue the  rise  of  liquid  beyond  the  limits  of  the  thistle  tube,  this 
should  be  replaced  by  a  long  glass  tube  —  say  three  feet  long  — 
before  closing  the  vent  and  clamping  in  place. 

Parallel  demonstration  of  starch  paste,  various  salts  and  sugars, 
or  of  different  concentrations  of  salts  and  sugars  may  be  made  by 
different  members  of  the  class.  The  diffusion  outward  should  not 


32  MANUAL  FOR  TEACHERS 

be  overlooked  in  the  presence  of  the  striking  inward  diffusion  of 
water.  The  discussion  of  the  results  should  bring  out  all  the 
important  facts  associated  with  the  idea  of  osmosis. 

Examples  of  diffusion  and  of  osmosis  in  everyday  experience, 
with  practical  applications,  should  be  called  for  and  recorded. 

References.  For  the  teacher:  COULTER,  BARNES,  and  COWLES,  Text- 
book, pp.  297-311  ;  LOEB,  Dynamics  of  Living  Matter,  lect.  iii.  For  the 
pupils:  ANDREWS,  Practical  Course,  pp.  52-58;  BERGEN  and  DAVIS,  Prin- 
ciples, chap,  v;  COULTER,  Plant  Life,  §§  35-36;  DUGGAR,  Plant  Physiology, 
chap,  iv ;  OSTERHOUT,  Experiments,  chap.  iii. 

XI.   ROOTS  OF  PLANTS 

To  obtain  root  hairs  suitable  for  class  study,  place  radish  seeds 
on  wet  blotting  paper  (blue  or  green)  in  Syracuse  watch  glasses 
or  Petri  dishes  two  or  three  days  before  they  are  to  be  used. 
There  should  be  no  free  water  standing  above  the  blotters.  Have 
dishes,  with  magnifying  glasses,  ready  to  pass  out  at  the  beginning 
of  the  study.  As  the  root  hairs  shrivel  up  on  exposure  to  the  air, 
the  dishes  should  be  taken  up  again  at  the  conclusion  of  the  study, 
and  stacked  up  for  use  with  another  class.  If  carefully  handled, 
the  preparations  should  serve  two  or  three  days.  Have  root  hairs 
of  tradescantia,  flax,  or  radish  mounted  for  examination  through 
the  compound  microscope. 

Fresh  woody  roots,  as  well  as  the  fleshy  roots  mentioned  in  the 
text,  should  be  on  hand  for  examination,  unless  it  is  feasible  to 
study  them  in  the  woods  or  fields. 

Have  on  exhibition  preparations  for  microscopic  views  of  the 
principal  kinds  of  root  tissue,  including  the  two  kinds  of  growing 
tissue,  —  cambium  and  terminal  meristem. 

To  show  the  dependence  of  root-hair  formation  upon  external 
conditions,  keep  roots  of  seedlings  in  water,  with  parallel  growths 
in  sand  or  paper.  Those  in  the  water  will  not  form  hairs. 

To  demonstrate  sap  pressure  or  root  pressure,  take  a  vigorous 
hydrangea  plant  with  stem  at  base  about  half  an  inch  thick,  place 
pot  and  base  of  plant  in  pail  of  water,  and  in  this  position  cut  off 
the  stem  about  two  inches  from  the  surface  of  the  soil.  Connect 


MANUAL  FOR  TEACHERS  33 

the  stem  with  a  glass  tube  by  means  of  a  rubber-tube  coupling. 
Remove  from  the  water  and  arrange  a  support  for  the  long  glass 
tube.  The  preparation  is  made  in  water  to  prevent  the  entrance 
of  air-bubbles. 

To  get  adventitious  roots,  place  various  twigs,  bits  of  begonia 
leaf  or  bryophyllum  leaf,  leaves  of  india-rubber  plant  or  of  English 
ivy  in  bottles  of  water. 

References.  BERGEN  and  CALDWELL,  Practical  Botany,  chap,  iii; 
BERGEN  and  DAVIS,  Principles,  chap,  iv ;  COULTER,  Elementary  Studies, 
Part  I,  chap,  xiii;  COULTER,  Plant  Life,  chap,  iv ;  COULTER,  BARNES,  and 
COWLES,  Textbook,  pp.  311-316;  DUGGAR,  Plant  Physiology,  chap,  iii; 
OSTERHOUT,  Experiments,  chap,  iii ;  United  States  Department  of  Agri- 
culture yearbooks ;  farmers'  bulletins. 

XII.   WHAT  FOOD  IS 

The  idea  of  activator  as  something  needed  to  keep  a  process 
going  may  be  illustrated  by  the  spark  in  the  gasoline  engine. 
The  drop  of  acid  added  to  water  to  make  the  latter  a  conductor, 
as  in  hydrolysis,  takes  no  part  in  the  main  process,  but  makes  the 
latter  possible. 

Regulator  is  illustrated  by  the  pendulum  of  a  clock  and  by 
the  balance  wheel  of  a  watch.  If  we  place  salt  in  the  water  before 
cooking  corn  meal  or  oatmeal,  we  thereby  regulate  the  temperature 
at  which  the  water  will  boil,  since  salty  water  has  a  higher  boiling 
temperature  than  pure  water.  The  gyroscope  is  another  example 
of  a  mechanical  regulator. 

The  school  museum  should  gradually  accumulate  specimens  of 
foods  in  a  pure  state,  —  casein,  albumens  of  various  kinds,  and 
other  proteins  may  be  obtained  in  the  market.  Starches,  sugars, 
and  fats,  with  the  sources  indicated  on  the  bottles,  are  helpful  in 
making  the  terms  stand  for  something  concrete,  and  in  correlating 
with  geography  on  the  one  hand  and  with  domestic  science  on 
the  other. 

References.  COULTER,  Plant  Studies,  pp.  41-42,  343-347 ;  COULTER, 
BARNES,  and  COWLES,  Textbook,  pp.  356-363;  HOUGH  and  SEDGWICK, 
The  Human  Mechanism,  pp.  86-95. 


34  MANUAL  FOR  TEACHERS 

XIII.    THE  ORIGIN  OF  FOOD 

For  conducting  the  experiments  in  photosynthesis,  hydrangea, 
coleus,  and  geranium  are  convenient  plants  to  use. 

To  show  the  relation  of  air  to  starch-making,  exclude  the  air 
from  a  leaf  upon  a  vigorous  live  plant,  by  smearing  vaseline  over 
both  surfaces,  on  one  side  of  the  midrib  only.  After  exposure  to 
bright  sunlight  for  a  whole  day,  remove  the  treated  leaf,  to  be 
tested  for  the  presence  and  distribution  of  starch.  To  remove  the 
chlorophyl  and  to  fix  the  starch,  boil  in  water  a  few  minutes,  then 
place  in  alcohol.  The  bleached  leaf  is  tested  for  starch  by  placing 
in  a  solution  of  iodin  in  10  per  cent  solution  of  potassium  iodid, 
about  the  color  of  weak  tea.  It  is  necessary  to  explain  that  starch 
is  the  only  substance  known  to  turn  blue  with  iodin. 

The  question  as  to  which  of  the  three  chief  gases  in  the  air  is 
concerned  in  starch-making  could  be  answered  by  means  of  an 
experiment,  if  it  were  desirable  to  do  so  in  the  laboratory.  Large 
bell  jars  connected  with  aspirators  for  drawing  a  current  of  air 
through  are  used.  A  live  potted  plant  is  placed  in  each  jar.  The 
inlet  pipe  of  one  jar  is  connected  with  a  wash  bottle  containing 
caustic  soda  solution,  to  withdraw  the  carbon  dioxid ;  a  second  jar 
is  thus  connected  with  a  phosphorus  container  for  removing  the 
oxygen ;  a  third  has  both  of  these  gases  removed.  The  control  is 
allowed  to  get  the  ordinary  atmospheric  mixture  of  gases. 

The  relation  of  light  to  photosynthesis  may  be  demonstrated 
either  by  using  two  plants,  one  in  the  light  and  one  in  the  dark, 
or  by  shielding  a  portion  of  a  leaf  from  light  while  the  rest  of  the 
plant  is  exposed.  The  latter  method  is  attained  by  pinning  two 
pieces  of  black  paper  on  the  opposite  sides  of  a  leaf  so  as  to 
exclude  the  light  from  the  covered  portion  without  excluding  the 
air,  and  leaving  the  rest  of  the  leaf  exposed  to  light  as  well  as  to 
air.  At  the  close  of  the  first  sunny  day  the  leaf  is  removed  from 
the  stem,  boiled  in  water,  and  soaked  in  alcohol.  The  application 
of  iodin  brings  out  the  distribution  of  starch. 

To  show  that  oxygen  is  liberated  during  photosynthesis,  place 
a  healthy  potted  plant  under  a  large  bell  jar  (with  an  opening  at  the 


MANUAL  FOR  TEACHERS  35 

top)  on  a  plate  of  glass.  Seal  the  base  of  the  bell  with  vaseline. 
Remove  the  oxygen  from  the  jar  by  burning  a  taper  lowered 
from  above.  Seal  the  top  opening.'  At  the  close  of  one  or  two 
sunny  days,  open  the  top  and  lower  a  lighted  taper  into  the  jar. 
The  difference  between  the  burning  conditions  at  the  beginning  of 
the  experiment  and  the  burning  conditions  at  the  close  points  to 
the  entrance  of  oxygen,  and  the  plant  is  the  only  apparent  source 
of  the  new  gas. 

To  explain  the  general  chemical  relations  of  the  materials 
involved  in  photosynthesis,  it  is  not  necessary  to  elaborate  much 
detail.  It  is  sufficient  to  bring  out  the  fact  that  the  hydrogen- 
oxygen  ratio  in  carbohydrates  is  the  same  as  that  in  water,  and 
that  the  utilization  of  water  and  carbon  dioxid  as  the  sources  of 
the  elements  entering  into  the  carbohydrates  leaves  a  surplus  of 
oxygen  corresponding  to  that  brought  in  with  the  carbon  dioxid. 

In  connection  with  this  study,  the  results  may  be  recorded  in  a 
table  showing  the  parallel  between  photosynthesis  and  a  manufac- 
turing process.  It  is  interesting,  if  there  is  time,  to  bring  out  at 
this  point  our  ultimate  dependence  upon  the  sun  for  all  the  energy 
that  we  utilize,  —  fuels  and  waterfalls  as  well  as  organic  processes. 
"  Every  action  is  a  transformed  sunbeam." 

References.  For  the  teacher :  COULTER,  BARNES,  and  COWLES,  Textbook 
of  Botany,  pp.  363-380;  DUGGAR,  Plant  Physiology,  chap.  ix.  For  the  pupils: 
ANDREWS,  Practical  Course,  pp.  168-174;  BERGEN  and  CALDWELL,  Prac- 
tical Botany,  pp.  15-17;  BERGEN  and  DAVIS,  Principles,  pp.  107-110; 
COULTER,  J.  G.,  Plant  Life,  pp.  43-44,  228-234;  COULTER,  J.  M.,  Ele- 
mentary Studies,  Part  I,  chap,  iii ;  OSTERHOUT,  Experiments,  pp.  182-203. 

XIV.   THE  CHEMICAL  CYCLE  OF  LIFE 

Have  specimens  of  clover,  alfalfa,  partridge  pea,  or  other  wild 
or  cultivated  legume  pulled  up  for  a  study  of  the  tubercles.  The 
balanced  aquarium  can  be  studied  profitably  with  reference  to  the 
essentials  of  the  balance.  Encourage  students  to  represent  their 
ideas  of  the  "  cycles  "  etc.  diagrammatically. 

Have  students  bring  news  items  bearing  on  the  current  or  local 
status  of  the  nitrogen  problem. 


36  MANUAL  FOR  TEACHERS 

References.  BERGEN  and  CALDWELL,  Practical  Botany,  pp.  374-378, 
447-451;  BERGEN  and  DAVIS,  Principles,  pp.  231-235;  DUGGAR,  Plant 
Physiology,  chap,  x;  SEDGWICK  and  WILSON,  General  Biology,  chap,  xvii; 
STILES,  Human  Physiology,  pp.  25-36. 

XV.   THE  SOIL  AS  THE  SOURCE  OF  OUR  MATERIALS 

The  purpose  of  this  chapter  is  to  combat,  on  the  one  hand,  gen- 
eral indifference  toward  the  problem  of  soil  use  and  conservation, 
and,  on  the  other  hand,  a  certain  fatalistic  Malthusianism.  We 
should  make  clear  that  population  and  prosperity  are  directly  re- 
lated to  the  amount  and  character  and  condition  of  the  soil ;  and 
that  applied  science  can  help  us  extend  our  power  and  resources 
indefinitely,  without  thought  of  exploiting  the  lands  of  other 
peoples.  Have  students  gather  data  on  reclamation,  irrigation 
projects,  etc.,  and  data  as  to  increased  production  per  capita  and 
per  unit  of  area. 

References.    See  references  to  VII;  L>UGGAR,  Plant  Physiology,  chap.  vi. 

XVI.   THE  LEAF  AS  STARCH  FACTORY 

The  concept  leaf  should  include  more  than  the  familiar  types. 
It  is  better  to  examine  cursorily  a  large  number  of  varieties  than 
to  study  minutely  a  few  forms.  All  the  extremes  afforded  by  the 
resources  at  hand  —  from  the  rhubarb  to  the  asparagus,  from  the 
cactus  to  the  cedar,  from  the  mullein  to  the  tradescantia  —  should 
be  brought  together  until  the  student  is  quite  convinced  that  the 
definition  of  leaf  is  not  to  be  found  in  a  description  of  a  few  or 
of  many  shapes. 

Examine  with  the  microscope  bits  of  epidermis  peeled  from  any 
convenient  leaves,  and  cross  sections  thin  enough  to  show  the 
tissues  and  if  possible  the  stomata. 

Comparing  the  leaf  to  a  factory,  have  students  make  diagrams 
showing  the  route  followed  by  materials  received  from  the  air  and 
from  the  stem  until  they  are  finally  disposed  of. 

To  measure  the  transpiration  of  a  potted  plant,  inclose  the 
pot  and  earth  in  rubber  sheeting  and  weigh  the  whole.  Weigh 


MANUAL  FOR  TEACHERS  37 

again  at  intervals  and  note  the  loss.  For  a  qualitative  demonstra- 
tion, the  prepared  potted  plant  may  be  placed  under  a  bell  jar; 
the  condensation  of  moisture  on  the  glass  will  indicate  loss  of 
water  from  the  plant  surface. 

To  show  the  pulling  force  of  the  transpiration  current,  insert 
the  stalk  of  a  healthy  leaf  in  the  end  of  a  glass  tube,  and  seal  the 
joint  with  paraffin.  Fill  the  tube  with  water  and  set  over  mercury. 
The  rise  of  mercury  in  the  tube  is  a  measure  of  the  mechanical 
equivalent  of  the  transpiration  from  the  leaf's  surface. 

Special  readings  and  reports  on  insectivorous  leaves. 

References.  ANDREWS,  Practical  Course,  pp.  189-195;  BERGEN  and  CALD- 
WELL,  Practical  Botany,  pp.  13-15,  18-20,  385-389;  BERGEN  and  DAVIS, 
Principles,  pp.  88-96,  102-106 ;  COULTER,  Plant  Life,  pp.  234-241,  251-255  ; 
COULTER,  BARNES,  and  COWLES,  Textbook  of  Botany,  pp.  521-530,  551-578, 
385-388,616-620;  DARWIN,  Insectivorous  Plants;  DUGGAR,  Plant  Physi- 
ology, chap,  v;  OSTERHOUT,  Experiments,  pp.  173-181,  203-223. 

XVII.   OUR  DEPENDENCE  UPON  LEAVES  AND  CHLOROPHYL 

This  is  in  part  a  repetition  of  the  thought  in  XIV,  The  Chemical 
Cycle  of  Life,  but  from  a  somewhat  different  point  of  view.  The 
attention  is  directed  to  the  concrete  materials  that  we  actually  use. 
Materials  used  in  connection  with  the  study  of  leaf  forms  and 
structure,  and  museum  material,  may  be  used  here.  Connect  the 
study  with  the  local  market  and  industrial  conditions. 

For  the  study  of  algae,  there  should  be  microscopic  prepara- 
tions or  good  charts.  Homemade  charts  that  will  serve  adequately 
can  be  prepared  with  a  little  effort. 

This  topic  furnishes  an  excellent  opportunity  for  a  synthetic  review. 

References.  COULTER,  Elementary  Studies,  pp.  378-383;  SARGENT, 
Plants  and  their  Uses,  §§  36,  137.  Yearbook  of  the  United  States  Depart- 
ment of  Agriculture,  an  variety,  magnitude,  and  values  of  crops. 

XVIII.    STARCH-MAKING  AND  DIGESTION 

Digestion  of  starch  can  be  demonstrated  by  using  a  very  thin 
starch  paste,  (a)  with  some  takadiastase  and  (£)  with  some  human 
saliva.  Use  large  test  tubes ;  keep  at  room  temperature  or  warmer. 


MANUAL  FOR  TEACHERS 


Demonstrate  starch  test  with  iodin  on  small  portion  drawn  off 
at  the  beginning  of  the  experiment.  Draw  off  at  intervals  of  five 
or  six  minutes  and  test  again.  When  there  is  no  more  starch 
present,  test  portion  from  each  test  tube  with  Fehling  solution. 
The  disappearance  of  the  starch  and  the  appearance  of  the  sugar 
(the  absence  of  which  may  be  demonstrated  at  the  beginning 
of  the  experiment)  indicate  that  something  has  happened  to  the 
starch  which  probably  has  something  to  do  with  the  formation  of 

sugar.  It  is  well  to 
test  the  diastase  with 
Fehling  solution  at  the 
beginning,  since  some 
commercial  diastase 
contains  reducing  sub- 
stances. 

A  more  striking  and 
otherwise  more  satis- 
factory demonstration 
consists  of  showing 
the  formation  of  dif- 
fusible substances  by 
the  action  of  diastase 

and  saliva.  Place  the  thin  starch  paste  with  saliva  in  a  celloidin 
bag  (see  p.  31  of  Manual),  and  starch  paste  with  diastase  in  an- 
other bag.  A  third  bag  (control)  contains  merely  starch  paste. 
The  three  bags  are  suspended  in  three  jars  or  tumblers  contain- 
ing clean  water.  After  the  expiration  of  fifteen  minutes,  withdraw 
some  of  the  surrounding  water  and  test  with  Fehling  solution. 
Repeat  from  time  to  time  until  there  is  a  positive  reaction.  Then 
put  a  few  drops  of  iodin  inside  each  bag.  The  bags  containing 
saliva  and  diastase  will  have  lost  their  starch  and  will  have  diffused 
sugar  into  the  surrounding  water ;  the  control  shows  no  change. 

Corn  grains  that  have  been  soaked  in  water  overnight  may  be 
tested  with  Fehling  solution  (after  being  cut  open,  some  length- 
wise and  some  crosswise).  Allow  some  of  the  soaked  grains  to 
sprout,  then  cut  them  open  and  test  them.  The  presence  of  sugar 
is  due  to  the  action  of  a  diastase  upon  the  starch. 


FIG.  8 


MANUAL  FOR  TEACHERS 


39 


References.  For  the  teacher :  COULTER,  BARNES,  and  COWLES,  Textbook 
of  Botany,  pp.  397-402  ;  DUGGAR,  Plant  Physiology,  pp.  265-271,  277-278  ; 
GREEN,  Vegetable  Physiology,  chap,  xvi ;  LOEB,  Dynamics  of  Living 
Matter,  lect.  ii.  For  the  pupils:  ANDREWS,  Practical  Course,  pp.  6-10; 
BERGEN  and  CALDWELL,  Practical  Botany,  pp.  144-146;  COULTER,  Plant 
Life,  pp.  350-352;  OSTERHOUT,  Experiments,  pp.  155-169. 

XIX.   DIGESTIVE  SYSTEM  IN  MAN 

If  microscopic  preparations  of  the  tissues  of  the  alimentary  canal 
are  available,  students  will  be  interested  in  examining  them ;  but 
they  are  not  essential.  Specimens  of  fresh  materials  obtained  from 
the  butcher  may  be  shown  to  those  who  are  not  squeamish.  None 
of  the  students  would  probably  object  to  examining  sausage  casing 
that  has  been  allowed  to  soak  in  water  until  soft.  A  satisfactory 
demonstration  of  peristalsis  consists  of  placing  a  marble  in  a  long 
piece  of  sausage  casing  and  driving  it  through  to  the  other  end 
by  pulling  the  casing  through  the  fingers  (see  Fig.  8).  • 

Ordinarily  it  is  not  worth  while  to  demonstrate  the  action  of  the 
various  digestive  ferments  of  the  alimentary  canal.  If  the  notion 
of  digestion  or  fermentation  is  clear,  it  is  sufficient  to  show  speci- 
mens of  pepsin,  peptone,  pancreatin,  ox-gall,  etc. 

A  good  way  to  summarize  this  study  is  to  have  students  make 
a  simple  diagram  representing  the  alimentary  canal,  and  to  label  it 
with  the  names  of  the  organs  on  one  side  of  the  drawing,  and  the 
names  of  the  processes  involved  on  the  opposite  side. 

Have  students  prepare  a  table  like  the  one  below,  and  fill  in 
all  the  blanks : 

THE  ACTION  OF  DIGESTIVE  JUICES  ON  FOODS 


ACTIVE  JUICES 

FOODS  DIGESTED 

RESULT  OF  ACTION 

Mouth     .... 

Stomach      .    .    . 

Intestines   .    .    . 

Another  form  of  summary  is  to  have  students  describe  the  fate 
of  an  imaginary  mouthful  of  food  containing  all  the  nutrients,  in 
its  course  from  the  mouth  to  the  large  intestine. 


40  MANUAL  FOR  TEACHERS 

References.  HOUGH  and  SEDGWICK,  The  Human  Mechanism,  chap,  viii ; 
STILES,  Human  Physiology,  chaps,  xiii-xv;  STILES,  Nutritional  Physiology, 
chaps,  xiv-xvi.  Have  pupils  make  special  reports  on  digestive  systems  and 
on  special  organs  of  various  vertebrate  and  invertebrate  types  or  groups. 


XX.   HEALTH  AND  FOOD  STANDARDS 

It  is  important  to  establish  a  clear  distinction  between  stand- 
ards that  represent  customs  or  usage,  and  norms  established  as 
the  result  of  experiment  or  measurement.  Have  students  present 
examples  of  usage  among  certain  people  who  have  remained  be- 
hind the  best  thought  and  knowledge  of  the  same  or  other  com- 
munities. Get  them  to  think  of  the  reasons  for  this,  and  of  methods 
for  accelerating  the  standardization  of  practice. 

Get  examples  of  food  fads  or  other  standard  usages,  with  the 
principles  offered  in  justification. 

Determining  units  for  measurement ;  get  examples  of  as  many 
kinds  as  the  students  happen  to  know.  As  a  demonstration,  deter- 
mine the  time  needed  to  raise  a  quantity  of  water  to  the  boiling 
point  in  a  given  vessel,  with  the  burner  in  use ;  compare  with 
results  when  using  double  quantity  of  water.  Or  use  similar 
quantities  with  different  size  of  flame. 

Explain  principle  of  calorimeter ;  if  there  is  one  in  town,  arrange 
to  visit  with  the  class  and  have  its  workings  demonstrated. 

Study  cases  in  which  standards  have  come  into  general  use 
after  scientific  determination. 

In  the  matter  of  food  standards,  bring  out  the  principle  of  indi- 
vidual variation.  This  should  be  referred  to  as  occasion  offers,  as 
one  of  the  fundamentals  of  modern  thinking  about  organic  and 
social  problems. 

To  give  the  daily  requirements  more  concrete  significance, 
have  the  students  calculate  the  mechanical  equivalent  of  the  energy 
represented  by  the  daily  ration.  For  example,  compare  the 
energy  consumed  by  the  organism  in  one  day  with  the  moving  of 
a  ton  of  freight,  with  the  raising  of  passengers  in  an  elevator  a 
given  .height,  with  the  lifting  of  a  quantity  of  ore  or  bricks, 
and  so  on. 


MANUAL  FOR  TEACHERS  41 

The  mechanical  equivalent  of  one  calorie  is  about  3,060  foot- 
pounds. One  horse-power  is  550  foot-pounds  per  second. 

References.  HOUGH  and  SEDGWICK,  Human  Mechanism,  pp.  211-217; 
ROSE,-  Feeding  the  Family,  chap.  i.  The  teacher  should  constantly  consult 
publications  of  research  laboratories,  such  as  those  of  Mendel,  Lusk, 
Chittenden,  Benedict,  etc.  See  United  States  Bureau  of  Standards, 
Circular  No,  55. 

XXI.  FOOD  REQUIREMENTS 

Have  each  student  prepare  a  schedule  of  one  meal,  or  of  a  day's 
meals,  and  then  go  through  the  calculations  according  to  the 
methods  used  in  the  text.  After  the  calculations  are  finished,  have 
the  food  assortments  of  specimen  charts  criticized  by  the  various 
standards.  Have  students  formulate  their  own  suggestions  for 
the  improvement  of  their  diet,  —  as,  eat  less ;  eat  less  fat  or 
protein ;  eat  more  vegetables ;  and  so  on. 

References.  FISHER  and  FISK,  How  to  Live,  pp.  28-35;  HOUGH  and 
SEDGWICK,  Human  Mechanism,  pp.  217-233;  LEE,  ROGER  I.,  Health  and 
Disease,  pp.  31-45;  ROSE,  Feeding  the  F'amily,  chap,  iii ;  STILES,  Human 
Physiology,  chap.  xxv.  Current  publications.  Have  special  reports  made 
on  rations  for  soldiers  or  for  various  institutional  groups. 

XXII.  FOOD  AND  DIETARIES 

It  would  be  interesting  and  illuminating  to  collect  examples  of 
superstitions,  folklore,  and  family  traditions  on  what  to  eat  and 
what  to  avoid.  Misleading  suggestions  on  the  choice  of  food  are 
frequently  found  in  advertisements  of  special  food  preparations,  and 
in  more  dogmatic  forms.  Many  obscure  pathological  conditions 
have  come  to  be  recognized  in  recent  years  as  due  to  disturbances 
in  nutrition  that  may  be  corrected  through  proper  adjustment  of 
the  diet.  The  students  should  be  encouraged  to  note  and  report 
experiences  and  observations  bearing  on  these  points.  Where 
there  is  an  opportunity  to  correlate  the  study  of  food  with  the 
domestic-science  work  of  the  school,  this  should  not  be  overlooked. 

In  the  study  of  food  economy  there  is  an  opportunity  for  a  great 
deal  of  practical  work,  and  this  is  readily  correlated  with  the 
domestic  science.  Using  Fisher's  tables,  have  students  obtain 


MANUAL  FOR  TEACHERS 


current  prices  of  the  various  foods,  and  calculate  the  cost  of  stand- 
ard (100  calorie)  portions.  An  interesting  piece  of  outside  work 
consists  of  preparing  a  series  of  bottles  or  specimen  jars  showing 
the  standard  quantity  of  each  of  a  series  of  food  articles,  together 
with  the  price  of  each.  A  parallel  series  might  be  prepared  by  an- 
other group  of  students,  showing  the  quantity  of  each  kind  of  food 
that  may  be  obtained  for  a  given  amount  of  money,  —  say  ten 
cents  or  five  cents.  The  labels  on  these  jars  should  contain,  of 
course,  all  the  significant  data,  as  in  the  two  labels  below : 


SERIES  A 

TEN  CENTS'  WORTH 

OF 
CORN  MEAL 


Quantity    . 
Calories 
Protein 
Prepared  by 
Date 


SERIES  B 
100  CALORIES 

OK 
OYSTERS 


Quantity    . 
Protein 
Cost      .     . 
Prepared  by 
Date 


Dry  food  materials  need  merely  to  be  sealed  in  the  jars  or 
bottles.  Meats,  fish,  fresh  vegetables,  etc.  can  be  preserved  in 
4  per  cent  formalin  solution.  Each  student  need  prepare  but  one 
or  two  specimens;  and  the  information  gathered  is  exchanged 
by  comparison  of  costs  and  other  data.  The  specimens  may  be 
kept  indefinitely,  and  the  collection  may  grow  from  year  to  year. 

References.  FISHER  and  FISK,  How  to  Live,  pp.  35-40;  HOUGH  and 
SEDGWICK,  Human  Mechanism,  pp.  233-243  ;  JORDAN,  E.  O.,  Food  Poison- 
ing, chap.  ix.  LEE,  Health  and  Disease,  pp.  54-68,  46-51  ;  RAPEER,  Edu- 
cational Hygiene,  pp.  68-77.  Special  readings  in  ROSE,  Feeding  the  Family. 
Have  students  compare  special  rations  established  for  domestic  animals, 
from  reports  of  agricultural  experiment  stations  and  from  the  United  States 
Bureau  of  Animal  Industry.  Current  matter  on  vitaminesand  on  deficiency 
diseases.  See  XX. 


MANUAL  FOR  TEACHERS  43 

XXIII.  FOOD  HABITS 

The  practical  value  of  these  studies  should  of  course  issue  in 
habits, — habits  of  attitude  as  well  as  habits  of  conduct.  It  is,  how- 
ever, extremely  difficult  to  gauge  the  extent  to  which  the  studies 
have  influenced  the  habits  of  the  pupils.  With  discretion  a  teacher 
may  from  time  to  time  put  forth  a  question  or  a  suggestion  that 
will  bring  an  illuminating  reaction  on  this  problem. 

For  a  study  of  the  teeth,  it  is  usually  easy  to  obtain  instructive 
specimens  from  a  dentist.  Cross  and  longitudinal  sections  may  be 
prepared  by  means  of  a  grindstone.  But  it  is  easy  to  spend  too 
much  time  on  the  study  of  tooth  structure  and  form  ;  these  are  not 
worth  much  unless  it  is  desired  to  make  a  fuller  study  of  compara- 
tive morphology  of  mammalian  teeth.  The  important  facts  are 
few  and  quickly  grasped,  and  are  related  to  decay. 

A  striking  demonstration  of  the  danger  of  exposing  the  teeth 
to  rapid  alternation  of  temperature  consists  of  heating  a  test  tube 
and  then  casually  dipping  it  into  a  jar  of  cold  water. 

It  has  been  found  very  instructive  to  make  a  census  of  the 
proprietary  drugs  on  sale  or  advertised  in  the  neighborhood,  for 
the  purpose  of  determining  the  proportions  of  those  offered  as 
remedies  for  headaches  and  constipation.  Labels  or  wrappers 
from  such  preparations  make  an  interesting  exhibit. 

References.  FISHER  and  FISK,  How  to  Live,  pp.  44-51,  51-57?  78-89; 
HOUGH  and  SEDGWICK,  Human  Mechanism,  chap,  xix ;  LEE,  Health  and 
Disease,  pp.  51-53;  ROSE,  Feeding  the  Family,  chap,  ii;  STILES,  Human 
Physiology,  chap,  xxvi ;  STILES,  Nutritional  Physiology,  chaps,  xxii,  xxiii. 
Special  readings  in  JORDAN,  Principles  of  Nutrition,  and  in  SHERMAN, 
Chemistry  of  Food  and  Nutrition.  Teacher  should  be  familiar  with  work 
of  Cannon  and  of  Carlson.  See  CANNON,  Bodily  Changes  in  Pain,  Hunger, 
Fear,  and  Rage,  chap.  i. 

XXIV.   THE  SOCIAL  SIDE  OF  THE  FOOD  PROBLEM 

Have  the  students  find  out  the  local  situation  in  regard  to  the 
protection  of  the  water  supply,  and  classify  the  functions  involved 
in  this  protection  in  order  to  see  how  much  depends  upon 
biological  principles. 


44  MANUAL  FOR  TEACHERS 

Have  the  students  obtain  copies  of  local  regulations  concerning 
food  standards,  food  protection,  and  food  sales.  Reports  of  the 
state  and  municipal  departments  of  health,  bureaus  of  weights 
and  measures,  milk  committees,  etc.  should  be  consulted. 

Collect  labels  from  various  food  packages,  showing  the  publica- 
tion of  facts  concerning  preservatives,  artificial  coloring,  etc.,  in 
accordance  with  specified  laws,  or  of  claims  as  to  purity  of  materials 
used.  It  is  impossible  to  know  ordinarily  the  extent  to  which  food 
is  "  faked."  But  reports  are  constantly  appearing  that  throw  light 
on  this  question,  and  students  should  know  both  how  to  obtain 
the  information  contained  in  such  reports  and  how  to  interpret  it. 
For  example,  the  New  Hampshire  Board  of  Health  issued  one 
report  in  which  it  appeared  that  of  three  hundred  and  sixty-three 
samples  of  food  taken  in  the  market,  nearly  one  half  (164  —  45.2 
per  cent)  were  adulterated.  Changes  in  the  attitude  of  official  and 
semiofficial  bodies  toward  this  matter  are  constantly  being  made, 
and  students  should  know  how  to  keep  in  touch  with  such 
changes.  For  example,  in  New  York  City  the  Board  of  Health 
began  in  1914  to  publish  every  week  the  names  of  all  dealers  or 
manufacturers  convicted  of  selling  foods  not  in  accord  with  offi- 
cial standards.  The  plan  of  publishing  names  and  addresses  of 
violators  has  been  especially  valuable  in  connection  with  the  milk 
business,  since  the  ordinary  milk  buyers  are  practically  helpless 
in  their  dealings  with  unscrupulous  sellers.  Newspaper  clippings 
should  be  pasted  in  notebooks  or  posted  on  the  class  bulletin. 

Have  students  report  on  conditions  in  stores  and  markets 
where  food  is  sold.  After  comparing  notes  in  class,  have  them 
draw  up  a  scale  for  scoring  or  grading  the  shops. 

Have  students  report  on  conditions  in  workshops,  stores,  fac- 
tories, and  offices,  in  relation  to  lunch-rooms,  opportunity  for  wash- 
ing up,  etc.  Much  of  this  information  can  be  obtained  by  inquiry 
among  relatives  and  acquaintances. 

Where  there  is  a  school  lunch  service,  it  should  be  possible  to 
cooperate  for  the  purpose  of  establishing  in  the  minds  of  the  pupils 
standards  in  regard  to  conditions  as  well  as  in  regard  to  the  food, 
balanced  rations,  quantities,  etc.  Have  students  prepare  schedules 


MANUAL  FOR  TEACHERS  45 

of  food  values  for  the  various  items  served  in  the  lunch-room,  and 
arrange  to  have  the  figures  used  in  connection  with  the  menus. 
If  this  is  already  the  practice,  sample  menus  may  be  used  as  basis 
for  discussion  of  balanced  rations  etc. 

Where  there  is  time,  it  is  worth  while  to  devote  a  whole  period 
to  the  subject  of  National  Food  Resources.  Begin  with  a  compari- 
son of  the  proportion  of  the  population  engaged  in  farming  at  the 
close  of  the  Civil  War  with  the  proportion  so  engaged  at  the  time 
of  the  last  census.  Then  compare  the  per  capita  production  of 
various  food  materials  at  the  two  periods ;  compare  the  yield  per 
acre  under  cultivation,  and  so  on.  The  point  to  be  brought  out 
is  the  increased  control  and  the  increased  resources  through  the 
application  of  biological  and  other  exact  knowledge.  Assign  indi- 
vidual students  to  report  on  the  various  governmental  activities 
related  to  the  food  yield  that  are  mentioned  in  the  text.  Bring 
out  the  realization  that  the  problem  of  food  conservation  means 
more  than  adequate  production ;  it  involves  matters  of  transporta- 
tion, marketing,  storage  and  preservation,  and,  finally,  adequate 
distribution  in  the  economic  sense,  —  that  is,  the  ultimate  consump- 
tion of  the  food  in  a  way  that  will  contribute  the  utmost  to  the 
welfare  of  the  nation  or  the  community. 

References.  HOUGH  and  SEDGWICK,  Human  Mechanism,  pp.  505-514; 
JORDAN,  Food  Poisons,  chaps,  v,  vi,  viii ;  LEE,  Health  and  Disease, 
pp.  69-73.  Special  reports  on  war  food  administration  ;  on  local  and  state 
regulations  of  food  production,  food  distribution,  and  food  standards ;  on 
current  studies  pertaining  to  character  and  extent  of  malnutrition  among 
children  or  other  groups ;  on  current  or  local  efforts  to  remedy  defects  of 
nutrition  in  large  groups.  Material  can  be  obtained  from  the  departments 
of  health,  commerce,  and  agriculture,  and  from  the  United  States 
Children's  Bureau. 


XXV.   STIMULANTS,  NARCOTICS,  AND  POISONS 

In  getting  the  idea  of  acclimatization,  the  students  will  be  led 
to  draw  upon  their  own  experiences  and  observations.  The  point 
to  emphasize  is  that  the  modified  organism  becomes  dependent 
upon  the  new  environment.  Whether  it  works  as  well  under 


46  MANUAL  FOR  TEACHERS 

the  new  conditions  as  it  can  under  the  natural  conditions  is  a 
different  question,  although  an  important  one. 

The  difficulty  that  many  students  have  in  forming  chemical  con- 
cepts may  in  part  be  met  by  the  use  of  mechanical  analogies,  which 
are  more  readily  visualized.  For  example,  in  thinking  about  the 
action  of  drugs  or  chemicals  upon  protoplasm,  compare  this  action 
to  the  effects  that  may  arise  from  introducing  a  foreign  body  into 
a  piece  of  machinery.  If  a  boy  should  stick  his  finger  into  the 
business  region  of  a  buzz-saw,  the  machine  would  keep  right  on 
working  as  though  nothing  had  happened ;  this  corresponds  to  an 
indifferent  chemical  body,  or  to  a  "  subliminal  dose."  If  the  boy 
should  drop  a  bar  of  iron  in  among  the  wheels,  it  might  catch  be- 
tween the  spokes  and  stop  the  machinery  altogether;  or  it  might 
catch  against  a  moving  part,  simply  slowing  up  the  machinery. 
This  corresponds  to  a  narcotic,  up  to  the  "  lethal  dose."  Finally, 
he  could  push  his  bar  of  iron  against  the  belt  connected  with  the 
governor  of  the  engine  and  disconnect  this  part ;  in  that  case  the 
engine  might  •  suddenly  begin  racing  at  increased  speed.  This 
would  correspond  to  the  effect  of  a  stimulant,  or  accelerator. 

References.  FISHER  and  FISK,  How  to  Live,  pp.  64-78, 250-268 ;  HOUGH 
and  SEDGWICK,  Human  Mechanism,  pp.  357-363 ;  LEE,  Health  and 
Disease,  pp.  125-134;  "The  Great  American  Fraud"  (American  Medical 
Association) ;  Farmers'  Bulletin,  "  Habit- Forming  Drugs." 

/    XXVI.  ALCOHOL  AND  HEALTH  -  XXVII.  ALCOHOL 
AND  SOCIETY 

We  must  be  on  our  guard  against  the  temptation  to  resort  to 
the  hortatory  method  in  dealing  with  this  subject ;  it  is  necessary 
to  maintain  a  more  calm  and  more  tolerant  spirit  than  that  which 
characterized  the  campaigners  of  a  generation  or  two  ago.  It 
happens  altogether  too  frequently  that  intelligent,  honest,  and 
likable  people  are  also  alcohol  drinkers.  The  awful  things  predi- 
cated about  drinkers  in  the  older  books  do  not  find  confirmation 
in  the  daily  experience  of  the  students.  Instead  of  discrediting 
the  drinkers,  these  experiences  discredit  the  books  and  the  whole 
tribe  of  physiology  and  hygiene  teachers. 


MANUAL  FOR  TEACHERS  47 

There  are  available  verified  and  verifiable  data  that  help  to 
demonstrate  the  undesirability  of  alcohol  as  a  beverage,  but  these 
data  are  to  be  used  in  a  common-sense  way.  We  must  avoid  the 
fallacy  of  arguing  from  statistical  generalizations  to  individual 
application.  It  is  impossible  to  say  "  You  will  suffer "  so  and  so 
if  you  drink.  The  very  most  that  we  can  say  is,  "  If  you  drink, 
your  chances  of  becoming  sick  are  increased  by  so  many  per  cent ; 
and  when  you  are  sick,  your  chances  of  recovery  are  reduced  by 
so  many  per  cent."  In  other  words,  the  data  show  simply  group 
effects.  We  may  therefore  teach  only  that  a  society,  or  community, 
or  class  of  people  stands  to  gain  by  adopting  this  or  that  course 
of  conduct.  Our  problem  is  to  socialize  the  interest  and  make  the 
individual  resolve  that,  so  far  as  he  is  concerned,  the  group  of  which 
he  is  a  member  is  to  profit  from  his  learning.  So  long  as  our 
health  teaching  in  regard  to  alcohol  (and  in  regard  to  many  other 
matters)  was  based  on  the  sentiment  of  competitive  advantages 
for  the  individual,  it  resulted  simply  in  placing  before  the  child 
the  betting  odds  against  the  practices  condemned.  And  since 
most  children  are  fairly  good  "  sports,"  the  teaching  did  not  suc- 
ceed in  intimidating  them.  The  individual  can  often  afford  to  take 
chances ;  the  only  certainty  we  can  teach  from  our  statistical  studies 
is  that  the  group  suffers  from  the  use  of  alcohol. 

To  demonstrate  the  effect  of  alcohol  upon  proteins,  add  alcohol 
to  the  raw  white  of  an  egg ;  this  is  a  suggestion  of  how  alcohol 
may  injure  protoplasm.  Supplement  with  parallel  demonstration 
of  the  coagulating  effect  of  mercuric  bichlorid  solution  and  other 
"  poisons."  The  point  is  to  show  that  alcohol  is  one  of  a  class 
of  substances  that  are  unquestioned  poisons,  and  not  something 
unique  in  its  relation  to  protoplasm. 

Have  students  gather  data  on  usages  of  local  employers,  in 
selecting  workers  for  responsible  positions,  in  the  matter  of  drink- 
ing. Have  them  get  information  as  to  regulation  of  the  patent- 
medicine  trade  by  local  or  general  authorities.  Have  reports 
made  on  fraudulent  cures  for  alcoholism.  What  are  the  current 
and  local  developments  in  meeting  the  social  requirements  of  the 
human  animal  that  had  been  left  to  the  exploitation  of  the  alcohol 


48  MANUAL  FOR  TEACHERS 

interests  in  the  past  ?  Agitation  and  legislation  since  the  entrance 
of  the  country  upon  the  war.  The  soldier  and  alcohol.  Opportuni- 
ties for  special  reports  and  studies  are  almost  limitless. 

References.  For  the  teacher:  BILLINGS,  Physiological  Aspects  of  the 
Liquor  Problem ;  KOREN,  Alcohol  and  Society.  For  the  pupils :  FISHER 
and  FISK,  How  to  Live,  pp.  227-250;  HOUGH  and  SEDGWICK,  Human 
Mechanism,  pp.  363-379;  LEE,  Health  and  Disease,  pp.  113-125.  An 
excellent  condensed  summary  of  all  the  significant  data  has  been  prepared 
by  the  D'Abernon-Newman  Committee  (British)  under  the  title  "  Alcohol : 
its  Action  on  the  Human  Organism."  An  American  edition  is  issued  by 
Longmans. 

XXVIII.    AIR  AND  LIFE 

Review  briefly  the  important  ideas  already  learned  on'  the  rela- 
tion of  oxygen  to  energesis  in  burning.  Have  live  plants  and 
animals  on  hand  for  demonstration  of  breathing. 

If  drawings  have  been  made  of  cross  sections  of  the  leaf,  refer 
to  them  and  add  further  notes  on  the  path  of  the  air  exchange 
involved  in  breathing.  If  there  are  no  drawings  and  there  is  not 
time  to  make  any,  use  wall  charts,  blackboard  drawings,  and 
microscopic  demonstration. 

If  the  season  permits,  use  live  insects  for  the  study  of  spiracles 
and  breathing  movements ;  otherwise  use  prepared  specimens. 
Study  tracheae  from  microscopic  mounts  and  from  pictures 
and  charts. 

Compare  live  earthworms  with  sandworms,  bloodworms,  or 
other  gill-bearing  worms  near  the  coast.  Use  preserved  speci- 
mens of  mollusks  and  crustaceans  for  comparison  of  different 
types  of  gills.  The  course  of  the  water  in  breathing  is  easily 
studied  in  crayfish  and  in  fish.  The  breathing  process  in  frogs 
should  also  be  studied  in  the  living  specimens.  The  test  of  the 
students'  grasp  of  the  mechanism  of  breathing  in  the  frog  lies  in 
their  answer  to  the  question,  "  What  would  happen  to  a  frog  that 
was  forced  to  keep  his  mouth  open  indefinitely  ?  " 

Prepare  in  advance  dissections  showing  the  connection  between 
the  throat  and  the  gill  slits  in  the  fish,  and  between  the  throat  and 
the  lungs  in  the  frog.  Some  of  the  older  students  can  make  such 


MANUAL  FOR  TEACHERS 


49 


dissections  under  direction.    Preserve  good  preparations  in  4  per 
cent  formalin  for  future  use. 

References.  BIGELOW,  Applied  Biology,  pp.  502-503.  Special  reports 
on  course  of  air  (oxygen)  in  the  breathing  of  various  vertebrate  and 
invertebrate  types,  from  descriptions  in  available  books  on  zoology 


XXIX.    BREATHING  IN   MAN 

Obtain  lungs  of  calf,  sheep,  or 
ox  from  a  butcher.  Use  models 
of  lungs,  showing  diagrammati- 
cally  some  of  the  detail  structure. 
For  making  clear  the  mechanics 
of  the  diaphragm  action,  the  appa- 
ratus pictured  in  Fig.  9  should  be 
set  up  in  advance.  If  there  is  a 
skeleton  in  the  school,  show  the 
relation  of  rib  curvature  and  rib 
movements  to  the  expansion  and 
contraction  of  the  chest  cavity. 

Have  students  study  the  move- 
ments of  the  chest  and  abdomi- 
nal wall  with  the  hands  while 
breathing  slowly.  Students,  es- 
pecially boys,  are  interested  in 
comparing  lung  capacity.  If  an 
aspirator  is  available,  or  records 
from  the  physical-training  de- 
partment, compare  lung  capacity 
with  chest  expansion.  Compare 
the  number  of  breaths  taken  by 
different  members  of  the  class 
in  one  minute ;  individual  variation ;  variation  in  depth  of  breath- 
ing of  different  pupils  at  the  same  time  and  of  the  same  pupils  at 
different  times.  Compare  the  number  of  breaths  per  minute  before 
and  after  some  vigorous  setting-up  exercises  in  the  laboratory. 


FIG.  9 

A  bell  jar,  closed  at  the  bottom  with 
rubber  sheeting,  and  at  the  top  with  a 
two-holed  stopper  carrying  (i)  a  Y-tube 
with  two  rubber  balloons,  and  (2)  a  glass 
vent  with  a  rubber  tube  closed  by  a 
pinchcock 


50  MANUAL  FOR  TEACHERS 

Demonstrate  by  the  pupils  themselves  relation  of  posture  to  chest 
expansion,  breaths  per  minute,  tidal  air.  Compare  notes  on  the 
effects  of  a  tight  belt  or  corset  and  other  features  of  the  clothing. 

References.  BIGELOW,  Applied  Biology,  pp.  503-505  ;  FISHER  and  FISK, 
How  to  Live,  pp.  18-28;  HOUGH  and  SEDGWICK,  Human  Mechanism, 
chap,  x;  STILES,  Human  Physiology,  chap.  xx. 


XXX.    VENTILATION 

In  speaking  of  ventilation  standards,  it  is  not  enough  to  learn 
figures  for  cubic  feet  per  hour  and  the  like.  Have  students 
measure  off  from  a  corner  of  the  room  enough  space  to  represent 
say  one  thousand  cubic  feet ;  have  them  get  an  idea  of  the  cubic 
capacity  of  the  classroom,  of  the  home  living-room,  of  the  bedroom, 
and  so  on. 

To  show  the  meaning  of  relative  humidity  in  relation  to  the 
work  of  the  lungs,  set  up  two  bell  jars  (or  inverted  battery  jars), 
suspending  in  each  a  piece  of  wet  filter  paper.  Under  jar  A  place 
a  dish  of  water;  under  jar  B,  an  empty  dish.  Note  the  time  in 
which  the  papers  become  dry ;  that  in  A  may  remain  moist  for 
weeks.  Compare  the  drying  of  clothes  on  a  clear  day  and  on  a 
muggy  day.  Introduce  the  wet-bulb  thermometer  and  show  how 
differences  between  wet-bulb  and  dry-bulb  readings  are  to  be 
interpreted.  Compare  the  lower  temperature  of  the  wet  bulb  with 
the  feeling  of  a  wet  spot  on  the  skin.  Make  clear  how  perspiration 
helps  to  regulate  the  body  temperature.  Use  the  illustration  of 
the  Australian  water  bottle. 

Have  students  report  on  standardized  usage  in  mines,  where 
low  oxygen  pressure  is  maintained  to  prevent  explosions. 

Establish  committees  of  students  to  be  responsible  for  the 
ventilation  and  temperature  of  the  classroom. 

References.  FISHER  and  FISK,  How  to  Live,  pp.  7-14;  HOUGH  and 
SEDGWICK,  Human  Mechanism,  chap,  xxviii ;  LEE,  Health  and  Disease, 
pp.  74-83.  Reports  of  current  investigations,  especially  on  ventilation  in 
industrial  establishments. 


MANUAL  FOR  TEACHERS  51 

XXXI.    CONTAMINATED  AIR 

The  dusty  trades  of  the  neighborhood  or  of  the  community,  and 
those  that  yield  injurious  vapors  or  fumes,  should  receive  special 
attention.  Have  students  find  out  what  these  industries  are  and 
what  conditions  prevail  for  the  safeguarding  of  the  health  of  the 
workers.  Are  there  any  regulations  or  difficulties  about  the  con- 
tamination of  the  community's  air  by  smoke  or  fumes  ? 

In  the  study  of  the  effects  of  tobacco,  keep  in  mind  the  limita- 
tions of  the  statistical  method,  as  suggested  in  the  notes  on  Chapters 
XXVI  and  XXVII,  and  the  further  sources  of  error  that  come  from 
the  possibility  of  the  tobacco  habit  being  in  itself  largely  a  selec- 
tive agent,  as  suggested  in  the  text.  In  a  school  containing  large 
numbers  of  boys  it  may  be  possible  to  collect  data  as  to  smok- 
ing and  non-smoking,  and  to  correlate  these  with  physical  and 
scholastic  records.  The  data  from  your  own  school,  or  from  a 
school  in  your  own  city  or  state,  will  carry  more  weight  than  those 
from  some  remote  institution.  Note  especially  the  current  and 
local  sentiment  and  tendencies. 

References.  HOUGH  and  SEDGWICK,  Human  Mechanism,  pp.  377-379; 
Bulletin  231,  United  States  Bureau  of  Labor  Statistics ;  Report  of  Y.  M.  C.  A. 
committee  on  experimental  study  of  the  effects  of  smoking. 

XXXII.     FIRST  AID  AND    HYGIENE  IN   RELATION   TO 
BREATHING 

Time  the  period  during  which  members  of  the  class  can  hold 
the  breath.  See  whether  those  with  unusually  high  records  have 
any  special  technique  that  enables  them  to  exceed  the  performance 
of  the  others. 

Artificial  respiration,  by  the  Schaefer  or  by  the  Silvester  method, 
should  be  demonstrated  and  practiced  by  the  members  of  the  class 
on  each  other.  If  there  is  an  emergency  hospital,  a  life-saving 
station,  a  fire-house,  or  other  similar  institution  within  reach, 
arrangements  should  be  made  for  the  demonstration  of  a  pulmotor 


52  MANUAL  FOR  TEACHERS 

or  other  like  device  for  the  establishment  of  normal  respiration 
after  asphyxiation,  drowning,  or  electric  shock. 

In  summarizing,  make  an  attempt  to  get  a  survey  of  the  prevailing 
habits  of  students  and  of  prevailing  home  conditions  with  reference 
to  these  matters, — as  open-air  sleeping,  mouth  breathing,  and  so  on. 

References.  Miners'1  Circular  No.  j,  United  States  Bureau  of  Mines ; 
Technical  Papers  Nos.  77  and  82,  United  States  Bureau  of  Mines  ;  RAPEER, 
Educational  Hygiene,  chap,  xv,  "  Open-Air  and  Open-Window  Schools." 


XXXIII.    TRANSFER   OF    MATERIALS    IN   PLANTS 

In  anticipation  of  this  study,  place  various  kinds  of  twigs  (pref- 
erably willow  twigs)  in  jars  of  water  to  form  roots.  Three  weeks 
or  longer  may  be  required.  Girdling  some  of  the  twigs  will  enable 
you  to  make-  clear  the  relation  between  the  bark  vessels  (phloem) 
and  the  transfer  of  elaborated  food  in  the  stem. 

Have  on  hand  microscopic  preparations,  especially  of  longitudinal 
sections  of  fibrovascular  bundles.  For  the  isolated  bundles,  use 
corn  stalks  or  celery,  either  fresh  or  preserved  in  from  2  per  cent 
to  3  per  cent  formalin.  For  explaining  the  exogenous  type  of 
structure  and  growth,  get  sections  of  various  dicot  or  coniferous 
twigs,  one  inch  or  more  in  diameter. 

To  show  the  distribution  through  the  wood  vessels  (xylem)  of 
stem  and  leaves,  place  seedlings,  stalks  of  celery,  or  small  succu- 
lent plants  with  roots,  in  tumblers  containing  dyed  water  (a  few 
drops  of  red  ink  added  to  the  water  will  do). 

In  connection  with  the  problem  of  the  ascent  of  sap,  recall  the 
pull  of  the  transpiration  current  and  the  demonstration  of  root 
pressure.  If  necessary,  repeat.  Get  the  idea  of  capillarity  clear  by 
means  of  glass  tubes  of  various  dimensions,  including  old  thermom- 
eter tubes  or  the  finest  tubes  you  can  get  by  drawing  out  a  glass 
tube  softened  in  a  Bunsen  flame.  Place  the  tubes  in  pigmented 
water  and  compare  the  heights  to  which  the  fluid  rises.  Suggest 
the  greater  .capillarity  of  the  microscopic  vessels  in  the  plant. 

In  connection  with  the  problem  of  the  descent  of  sap,  discuss 
thoroughly  the  behavior  of  girdled  trees.  Is  the  sap  of  the  maple 


MANUAL  FOR  TEACHERS  53 

obtained   from  the   ascending  or  from  the  descending  current  ? 
What  is  the  evidence  ? 

Study  commercial  fibers  (chiefly  bast,  such  as  flax,  hemp,  jute), 
bark  fibers,  etc.  Correlate  with  commercial  geography. 

References.  For  the  teacher :  COULTER,  BARNES,  and  COWLES,  Text- 
book of  Botany,  pp.  388-397,  678-696 ;  DUGGAR,  Plant  Physiology,  pp.  272- 
273,  278-279.  For  the  pupils:  ANDREWS,  Practical  Course,  pp.  112-118; 
BERGEN  and  DAVIS,  Principles,  chap,  viii ;  OSTERHOUT,  Experiments, 
pp.  224-258. 

XXXIV.    THE   BLOOD 

Obtain  blood  from  a  butcher  or  from  a  slaughterhouse.  Add  a 
little  formalin  to  prevent  decomposition. 

Demonstrate  clotting  and  the  formation  of  serum  by  allowing 
the  blood  to  stand  quietly  in  a  covered  battery  jar  or  beaker. 

Whip  some  blood  in  a  battery  jar  with  an  egg-beater  or  a  whisk 
of  small  twigs.  The  beating  withdraws  the  fibrin  from  the  blood 
as  fast  as  it  is  formed.  Allow  some  of  this  whipped  blood  to 
stand  alongside  the  other ;  when  the  clot  is  formed  in  the  first, 
the  second  still  remains  fluid. 

Wash  the  corpuscles  out  of  the  clot  with  cold  water ;  show  its 
fibrous  structure  and  its  protein  composition,  using  nitric  acid 
followed  (after  washing)  with  ammonia. 

Examine  human  blood  under  the  microscope,  placing  a  drop  in 
a  little  salt  solution. 

Pass  oxygen  through  defibrinated  blood  contained  in  a  tumbler ; 
pass  carbon  dioxid  through  another  specimen.  See  pages  11-13 
for  the  preparation  of  gases. 

Compare  the  lymph  to  the  ocean  as  the  medium  of  primordial 
life. 

Point  out  that  certain  types  of  bleeders  suffer  from  the  failure 
of  the  blood  to  form  a  clot,  whereas  in  other  cases  the  defect  is 
in  the  texture  of  the  capillaries. 

References.  BIGELOW,  Applied  Biology,  pp.  53-55,  482-486;  HOUGH 
and  SEDGWICK,  Human  Mechanism,  pp.  132-135;  STILES,  Human 
Physiology,  chap.  xvi. 


54  MANUAL  FOR  TEACHERS 

XXXV.    THE  CIRCULATION  OF  THE  BLOOD 

Demonstrate  the  circulation  of  blood  in  the  web  of  a  frog's  foot 
or  in  the  tail  of  a  tadpole.  To  keep  the  animal  quiet  while  on  the 
stage  of  the  microscope,  it  may  be  chloroformed ;  but  you  must 
be  careful  not  to  expose  it  too  long  to  the  fumes  of  the  anesthetic. 
Place  the  frog  in  a  battery  jar  in  which  is  suspended  a  wad  of 
cotton  containing  the  chloroform,  and  cover.  The  low  power  of 
the  microscope  is  sufficient  Point  out  that  the  large  pigment  cells 
are  not  in  the  blood ;  these  cells  are  often  confusing. 

Demonstrate  the  structure  of  a  beef  or  calf  heart ;  get  good 
models  if  these  are  available. 

Have  students  tabulate  data  as  to  the  circulation  and  as  to  the 
changes  that  take  place  in  the  blood  in  various  parts  of  its  course. 

Note  the  exception  to  the  rule  that  "  blood  goes  from  arteries  to  capil- 
laries and  from  capillaries  to  veins,"  —  namely,  the  portal  circulation. 

References.  HOUGH  and  SEDGWICK,  Human  Mechanism,  pp.  136-149; 
STILES,  Human  Physiology,  chaps,  xvii,  xviii. 

XXXVI.    HYGIENE  OF  THE  CIRCULATORY   SYSTEM 

Have  students  find  and  count  their  pulses  for  a  given  time 
(as  for  one  minute),  and  record.  Have  the  class  stand  up  and  go 
through  setting-up  exercises,  and  then  record  the  pulse  again. 

If  a  stethoscope  is  available,  have  them  listen  to  their  own 
heartbeats  and  to  any  particularly  interesting  cases,  as  of  mur- 
murs etc.  Call  attention  to  the  evidence  of  danger  in  overtraining 
in  athletics,  —  for  example,  the  experience  of  naval  cadets  in 
after  life. 

Present  a  collection  of  antiseptics  suitable  for  the  treatment  of 
wounds  and  scratches.  Study  bandages. 

Demonstrate  methods  for  stopping  bleeding,  including  nose- 
bleed. Demonstrate  the  use  of  the  tourniquet.  Study  the  use 
of  astringents. 

Have  students  tabulate  the  results  of  their  study,  —  types  of 
situations  and  treatment,  appliances,  etc. 


MANUAL  FOR  TEACHERS  55 

Have  students  tabulate  the  factors  that  have  an  influence  upon 
the  condition  of  the  blood,  and  the  results  of  various  derangements, 
—  as  food,  bowel  habits,  breathing,  rest  and  fatigue,  stimulants 
and  narcotics,  and  so  on. 

References.  For  the  teacher  :  CANNON,  Bodily  Changes  in  Pain,  Hunger, 
Fear,  and  Rage,  chaps,  iii,  v,  ix,  x ;  HOUGH  and  SEDGWICK,  Human 
Mechanism,  pp.  149-161;  LEE,  Health  and  Disease,  chap,  v;  STILES, 
Human  Physiology,  chap.  xix. 

XXXVII.    THE  BLOOD  AS   A  LIVING  TISSUE 

Review  white  corpuscles  in  terms  of  the  properties  and  behavior 
of  naked  protoplasm,  emphasizing  especially  types  of  irritability. 
Have  on  hand  specimens  of  antitoxin,  vaccine  for  typhoid  and 
smallpox,  and  other  serum  preparations.  Culture  tubes  and  swabs 
for  diphtheria  cultures  should  be  seen  and  handled,  and  their  use 
demonstrated. 

The  idea  of  a  precipitate  can  be  represented  very  easily :  add 
some  sulfate  solution  to  a  solution  of  barium  chlorid. 

The  subject  is  usually  very  interesting  to  young  people,  and 
leads  to  many  questions.  The  teacher  should  be  prepared  to 
answer  some  of  these  concretely  and  specifically,  —  as  the  dosage 
for  antitoxin,  the  unit,  and  how  it  is  determined ;  the  use  of  serum 
methods  in  diagnosis  and  in  the  specific  identification  of  animal 
or  other  organic  material ;  the  use  of  the  opsonic  index ;  the 
diseases  against  which  vaccination  has  been  successfully  used  ;  the 
arguments  pro  and  con  on  compulsory  vaccination ;  the  phenomena 
of  anaphylaxis  ;  and  so  on. 

Get  examples  of  individual  variations  in  natural  immunity  and 
racial  variation.  Experience  of  students  with  acquired  immunity, 
whether  the  result  of  disease  or  of  special  treatment ;  data  on  the  rela- 
tion of  temperature,  fatigue,  nutritive  conditions,  etc.  to  immunity. 

The  subject  of  heredity  often  obtrudes  itself  insistently  and 
must  be  handled  firmly.  To  differentiate  between  the  inheritance 
of  a  disease  and  the  inheritance  of  a  natural  susceptibility  is  not 
difficult  if  the  specific  relation  between  bacteria  and  disease  has 
been  first  made  clear.  But  when  it  is  necessary  to  speak  of  a 


56  MANUAL  FOR  TEACHERS 

possible  infection  of  an  infant  within  the  body  of  the  mother, 
many  teachers  balk  and  make  trouble  for  themselves.  Draw  upon 
the  local  department  of  health  and  the  hospitals  for  help. 

References.  BUCHANAN,  Household  Bacteriology;  HOUGH  and  SEDG- 
WICK,  pp.  497-504.  Special  reports  on  the  history  of  smallpox  vaccina- 
tion ;  on  experience  of  the  army  with  typhoid  vaccination ;  on  the  work 
of  Behring,  Metchnikoff,  etc. 

XXXVIII.    WASTES   AND   BY-PRODUCTS   OF  ORGANISMS 

Review  chemical  changes,  with  special  emphasis  upon  the  forma- 
tion of  new  substances.  Cell  metabolism  involves  the  formation 
of  new  substances ;  some  of  these  are  indifferent  (water),  some 
are  useful  (proteins),  and  some  (carbon  dioxid,  urea,  various  acids) 
are  injurious,  at  least  in  excessive  quantities. 

Grow  some  young  seedlings  in  a  moist  chamber  or  under  wet 
paper,  in  contact  with  a  polished  piece  of  marble.  The  etching 
of  the  stone  shows  the  action  of  some  add,  but  chemical  studies 
fail  to  reveal  any  organic  acid  secreted  by  the  roots.  The  car- 
bon dioxid  (respiration  product)  in  the  water  is  sufficient  to 
dissolve  the  carbonate  of  lime.  Guard  against  the  teachings  of  some 
of  the  older  books,  which  still  point  to  the  etching  as  indicating  an 
adaptation  for  dissolving  mineral  matter.  Some  of  the  dissolved 
mineral  may  be  absorbed  by  the  roots,  but  the  secretion  is  of  the 
same  character  as  our  exhalation  of  carbon  dioxid  through  the  nose. 

Compare  the  accumulation  of  insoluble  materials  in  the  tissues 
of  plants  with  the  deposit  of  starch  etc.  in  tubers  and  other 
storage  organs. 

Microscopic  demonstration  of  pigments ;  chloroplasts  as  well  as 
sap  pigment  may  be  found  in  the  corolla  of  the  pansy. 

Study  museum  specimens  of  tannin  and  its  sources.  Give  a 
demonstration  of  tanning  (as  of  white  of  egg)  and  of  tannery 
products.  Study  specimens  of  other  plant  products, —  essential 
oils,  alkaloids,  acids,  etc.  Correlate  with  commercial  geography. 

Microscopic  demonstration  of  silica  and  raphides  in  plant  cells : 
use  scouring  rush  (Equisetum)  for  the  former,  and  Indian  turnip 
(Arisfzmd)  for  the  latter. 


MANUAL  FOR  TEACHERS  57 

Study  the  Paramecium  again,  with  special  attention  to  the  con- 
tractile vacuole.  Any  other  available  protozoa  would  do  as  well. 

Cut  kidney  of  calf  or  sheep  lengthwise  to  show  gross  structure. 
Show  microscopic  preparations  of  kidney  for  gland  structure. 
Microscopic  sections  of  the  skin  are  usually  not  satisfactory  for 
those  unskilled  in  the  use  of  the  microscope.  A  better  idea  of 
skin  structure  is  to  be  obtained  from  a  good  model. 

References.  COULTER,  BARNES,  and  COWLES,  Textbook  of  Botany, 
pp.  412-416,  620-626,718-725;  HOUGH  and  SEDGWICK,  Human  Mechanism, 
pp.  177-186 ;  SARGENT,  Plants  and  their  Uses,  chaps,  iv,  v  ;  STILES,  Human 
Physiology,  chap,  xxiii. 

XXXIX.    HYGIENE  OF  EXCRETION 

What  are  the  local  and  state  regulations  regarding  the  provision 
of  drinking  water  in  shops,  factories,  etc.  ?  What  are  the  local 
usages  in  this  respect,  and  as  to  public  drinking  fountains  ? 

To  what  extent  is  there  need  for  official  regulation  regarding 
the  provision  of  adequate  toilets  and  washing  facilities  in  industrial 
and  commercial  establishments  ?  public  comfort  stations  ? 

What  are  the  public  bathing  facilities  ?  What  are  the  tendencies 
as  to  home  bathing  ? 

How  much  water  (and  fluid  with  food)  does  each  of  us  take 
in  during  the  day  ? 

Relation  of  physical  exercise  to  circulation  and  excretion ;  why 
perspiration  is  healthful. 

References.  FISHER  and  FISK,  How  to  Live,  chap,  iv;  HOUGH  and 
SEDGWICK,  Human  Mechanism,  pp.  413-424;  LEE,  Health  and  Disease, 
chap.  iv. 

XL.  EXCRETION  AND  FATIGUE  — XLI.  FATIGUE  AND 
THE  WORKER 

Use  a  dynamometer  from  the  gymnasium,  or  a  spring  scale 
from  the  physics  department,  to  explain  the  principle  of  the  ergo- 
graph.  Have  a  number  of  students  make  records  at  the  beginning 
of  the  day  and  again  at  the  close  ;  or  get  records  of  gymnasium  per- 
formance, as  "chinning,"  made  at  intervals  involving  work  and  rest. 


58  MANUAL  FOR  TEACHERS 

Compare  experiences  with  fatigue  and  endurance. 

Have  students  make  special  reports  on  the  introduction  of 
"  scientific  management,"  or  "  standard  motions,"  in  local  indus- 
trial or  commercial  establishments,  or  on  readings  upon  the  sub- 
ject. Have  special  reports  on  the  findings  of  the  Health  of 
Munitions  Workers  Commission. 

Collect  data  on  hours,  variations  in  work,  pauses,  and  overtime 
in  local  establishments.  What  are  the  local  or  general  regulations 
in  these  matters  ?  To  what  occupations  do  they  apply  ?  What 
occupations  are  explicitly  exempted  ?  Why  this  discrimination  ? 

Get  information  on  the  distribution  of  accidents  in  industries 
during  the  day ;  during  the  week ;  during  the  year.  Have  students 
plot  graphs  and  analyze  on  physiological  grounds. 

Compare  also  records  of  school  tests  made  with  a  view  to 
measuring  the  influence  of  accumulating  fatigue  upon  attention  etc. 

Show  how  exercise  of  the  large  muscles  helps  to  rest  the 
sedentary  worker  by  accelerating  the  blood  flow  and  facilitating 
perspiration. 

References.  CANNON,  Bodily  Changes  in  Pain  etc.,  chaps,  vi-viii; 
GOLDMARK,  Fatigue  and  Efficiency ;  HOUGH  and'  SEDGWICK,  Human 
Mechanism,  chap,  v,  pp.  314—320;  LEE,  Health  and  Disease,  chap.  v. 
Bulletins  and  current  reprints  of  the  United  States  Public  Health  Service ; 
Bulletins  of  the  United  States  Bureau  of  Labor  Statistics. 

XLII.    NERVES   AND  THE  REACTIONS   OF   ORGANISMS 

Demonstrate  some  of  the  common  reflexes  by  the  students 
themselves.  The  knee-jerk  is  interesting  and  amusing  when  intro- 
duced for  the  first  time,  and  it  gives  food  for  thought.  Feed  live 
worms  to  frogs  in  the  laboratory,  or  use  a  dangling  bit  of  red 
worsted.  Have  students  report  experiences  in  fishing,  or  with 
wild  birds,  or  with  domestic  animals.  Refer  to  the  coughing  reflex, 
and  to  sneezing  and  vomiting.  Have  students  report  their  own 
observations  and  examples.  The  gland  reflex  that  is  most  familiar 
is  that  of  the  mouth  watering,  but  the  cold  sweat  is  perhaps  not 
altogether  strange  (although  this  is  not  the  same  kind  of  reflex  as 
the  others  mentioned). 


MANUAL  FOR  TEACHERS  59 

Have  prepared  microscopic  slides  showing  nerve  structure.  It 
is  hardly  worth  while  to  study  the  muscle  under  the  microscope. 

Under  chloroform  dissect  out  the  long  muscles  of  a  frog's  leg,  with 
the  associated  nerve ;  stimulate  with  the  electric  current  from  two 
battery  cells.  Show  contraction  in  response  to  the  stimulation  of  the 
nerve  and  in  response  to  the  direct  stimulation  of  the  muscle  itself. 

The  dependence  of  the  muscle  upon  the  nerve  connections  may 
be  suggested,  though  not  strictly  demonstrated,  by  bending  the 
middle  finger  forward  until  the  tip  is  opposite  the  palm  of  the 
hand,  as  in  Fig.  10.  The  nerve  fibers  connected  with  the  muscles 
controlling  the  end  segment  are  com- 
pressed and  apparently  inactive.  The  end 
joint  may  be  moved  about  (by  the  other 
hand)  and  seems  lifeless. 

Use  a  pithed  frog  or  one  in  which  the 
cord  is  severed  back  of  the  medulla,  to 
demonstrate  the  persistence  of  useful  re- 
flexes independently  of  the  higher  centers. 
Refer  also  to  the  chicken  that  runs  around 
after  the  head  is  cut  off.  Have  students 
suggest  other  examples. 

Recall  the  increase  in  pulse  rate  on  FlG 

taking  exercise,  as  an  example  of  a  reflex 

that  does  not  shunt  any  impulses  into  the  brain  cortex.  The 
increased  heart  work  is  due  to  a  series  of  reflexes  involving 
chemical  stimulation  (the  partial  pressure  of  carbon  dioxid  in 
the  blood)  and  muscular  reactions,  but  no  conscious  sensation 
and  no  voluntary  influence  upon  the  heart  muscles  or  upon  the 
breathing  mechanism. 

Point  out  the  fallacy  of  assuming  that  the  reflexes,  or  the  natural 
behavior,  of  organisms  are  necessarily  adaptive.  The  feeding 
of  nearly  all  animals  depends  upon  reflexes,  and  the  escape  from 
enemies  also  involves  reflexes.  If  the  reflexes  were  perfect,  the 
frog  would  catch  every  fly  he  tries  to  catch,  and  the  fly  would 
escape  from  every  frog  that  tried  to  catch  him ;  the  victim  (food) 
would  be  assured  to  the  feeder,  and  the  safety  of  the  prey  would 


60  MANUAL  FOR  TEACHERS 

be  equally  assured,  and  the  feeder  would  starve.  Have  pupils  find 
illustrations  of  the  principle  that  some  reflexes  are  indifferent,  that 
some  are  even  injurious,  and  that  none  are  perfect  as  adaptations. 

References.  For  the  pupils:  HOLMES,  Animal  Biology,  chap,  xxiii; 
HOUGH  and  SEDGWICK,  Human  Mechanism,  chaps,  vii,  xv.  For  the 
teacher:  DONALDSON,  Growth  of  the  Brain;  LOEB,  Comparative  Physiology 
of  the  Brain ;  STILES,  Human  Physiology,  chaps,  vii,  vi,  viii,  ix ;  STILES, 
The  Nervous  System. 

XLIII.    TROPISMS  AND  THE  BEGINNINGS  OF  SENSE 

The  idea  of  a  general  reaction  is  not  so  strange  as  it  may  at  first 
appear.  Recall  that  the  child  winks  not  only  when  something 
approaches  the  eye,  but  also  when  he  hears  a  sudden,  loud  sound, 
or  when  he  is  startled.  The  flight  of  the  bird  may  be  initiated  by 
many  different  stimuli;  a  worm  contracts  in  response  to  many 
different  stimuli ;  the  ameba  shrinks  into  a  spherical  mass  in 
response  to  many  different  stimuli ;  and  so  on.  Compare  seeing 
stars  when  the  head  is  struck.  The  students  will  no  doubt  brin^ 
further  examples,  once  they  get  the  idea. 

Experiments  on  the  senses  are  always  interesting  and  may  be 
devised  in  endless  variety.  Have  the  students  work  in  pairs. 

To  get  differences  between  various  parts  of  the  skin  in  respect 
to  discrimination  in  touch,  use  compasses  with  the  points  close 
together  and  gradually  opened  apart,  noting  the  smallest  separation 
that  can  be  distinguished  as  two  points  in  the  different  parts  of 
the  skin  tried,  —  as  the  back  of  the  hand,  the  neck,  tips  of  fingers, 
tip  of  tongue,  wrists,  face,  etc. 

For  the  hot  and  cold  points,  try  series  of  points  on  the  palm 
of  the  hand,  guiding  by  the  folds.  Use  bits  of  wire  or  nails 
about  two  inches  long.  Place  nails  in  hot  water  (about  80  degrees 
C.)  and  some  in  cold  water  (about  5  degrees  to  10  degrees  C.). 
Change  as  soon  as  the  temperature  of  the  nail  approaches  that 
of  the  skin  closely.  Have  the  students  try  the  hot  and  cold  points 
on  the  cheeks. 

For  experiments  with  taste,  use  dilute  solutions  of  salt,  sugar, 
acetic  acid  (vinegar),  and  very  dilute  solutions  of  quinine  or  aloes. 


MANUAL  FOR  TEACHERS  6 1 

With  a  glass  rod  drawn  to  a  very  fine,  rounded  point  (and  rinsed 
clean  after  each  use),  have  the  students  find  and  chart  the 
distribution  of  the  various  papillae  on  the  tongue. 

For  showing  the  relation  of  odors  to  flavor,  have  various  sub- 
stances (foods,  spices,  condiments)  placed  in  the  mouth  of  a 
blindfolded  student,  holding  his  nose  to  prevent  the  inhalation  of 
vapors  from  the  air  or  from  the  pharynx.  Record  the  discrimi- 
nations made,  either  by  naming  the  substances  recognized  or  by 
describing  them. 

Call  attention  to  the  danger  of  interpreting  movements  of 
organisms  in  terms  of  likes  and  dislikes  in  the  absence  of  real 
knowledge  about  the  emotions  involved.  Earlier  natural  philosophy 
of  all  peoples  appears  to  take  this  form,  and  it  is  indeed  difficult 
to  think  of  energies  except  as  attractions  and  repulsions ;  but  we 
may  learn  to  use  these  terms  without  implying  what  usually  goes 
with  them  when  applied  to  human  conduct. 

References.  For  the  pupils:  CLODD,  The  Childhood  of  the  World, 
Part  II ;  HOLMES,  Studies  in  Animal  Behavior,  chaps,  i-v ;  HOUGH  and 
SEDGWICK,  Human  Mechanism,  pp.  263-265.  For  the  teacher:  HOLMES, 
-Evolution  of  Animal  Intelligence,  chaps,  iii,  iv  ;  LOEB,  Forced  Movements ; 
LOEB,  The  Organism  as  a  Whole,  chap,  x ;  MORGAN,  Evolution  and  Adap- 
tation, chap,  xi ;  WATSON,  Behavior,  chaps,  i-iii. 

XLIV.    EYES   AND  LIGHT 

It  is  not  difficult  to  keep  Euglena  in  the  aquarium,  and  in  suffi- 
cient quantities  to  show  the  collection  of  the  organisms  on  the 
illuminated  side  and  the  reversal  of  the  tropism  on  exposure  to 
direct  sunlight.  The  idea  of  reaction  depending  on  physiological 
state  should  offer  no  serious  difficulties.  Compare  the  effect  of 
seeing  tempting  food  before  a  meal  and  after  a  meal.  The  mouth 
does  not  water  so  readily  when  one  is  replete.  So,  a  tired  boy  is 
not  aroused  by  temptations  that  would  ordinarily  lead  him  to  great 
exertions ;  when  one  is  ill,  he  wants  none  of  the  amusements  that 
ordinarily  appeal  to  him  ;  and  so  on.  The  students  can  furnish 
abundant  illustrations  from  their  own  experience.  The  point  to 
keep  clear  is  that  the  protoplasm  can  be  modified  in  its  conduct 


62  MANUAL  FOR  TEACHERS 

by  the  presence  or  absence  of  various  substances,  by  temperature, 
by  light,  and  by  other  incident  forces. 

Hydra  and  frogs  are  also  valuable  for  showing  the  light 
tropisms  and  the  influence  of  intensity.  Earthworm  habits  are 
known  to  many  boys.  Assign  for  special  report  the  behavior  of 
earthworms  under  varying  intensity  of  illumination;  and  the 
behavior  of  various  water  animals,  including  fishes. 

Compound  eyes  of  insects  or  other  arthropods  should  be 
examined ;  have  also  microscopic  preparations  of  eye  surface 
and  eye  section. 

A  good  model  of  the  human  eye  is  almost  essential  for  a  satis- 
factory study  of  this  topic,  but  good  charts  may  be  acceptable 
substitutes.  A  box  camera  that  is  readily  taken  apart  will  be  of 
help ;  get  one  that  has  a  focusing  screen  of  ground  glass.  Have 
the  students  study  the  pupil  reflex  with  changing  illumination, 
working  in  pairs.  Rarely  a  person  is  found  who  can  control  the 
movement  of  the  iris.  It  is  probable  that  in  most  cases  the  control 
is  indirect,  —  the  subject  produces  the  movements  by  changing  the 
focus  while  appearing  to  be  staring  fixedly,  or  he  does  so  by 
imagining  sudden  changes  from  extreme  light  to  extreme  dark; 
or  the  reverse.  This  is  in  a  way  similar  to  making  the  mouth 
water  by  thinking  of  good  things  to  eat. 

The  students  should  finish  this  study  with  the  conviction  that 
many  of  the  movements  of  organisms  are  quite  as  mechanical  as 
those  of  a  machine ;  and  they  should  be  as  ready  to  give  up 
attributing  to  emotions  the  movements  of  animals  as  they  would  be 
to  deny  emotion  to  a  phonograph  reproducing  sentimental  ballads. 
In  the  case  of  the  animals,  as  in  that  of  the  phonograph,  the 
phenomena,  including  the  emotions,  are  produced  because  the 
thing  is  built  thus  and  so. 

References.  For  the  pupils :  HOUGH  and  SEDGWICK,  Human  Mechanism, 
pp.  244-258.  For  the  teacher:  HOLMES,  Evolution  of  Animal  Intelligence, 
chap,  vii;  STILES,  Human  Physiology,  chap,  xi ;  WATSON,  Behavior,  chap.  xi. 
For  reversal  of  tropisms :  LOEB,  Forced  Movements,  chaps,  v-xi,  xii,  xix. 


MANUAL  FOR  TEACHERS  63 

XLV.    HYGIENE  OF   THE  EYES 

Where  students'  eyes  are  not  regularly  examined,  arrange  for 
examination  with  Snellen's  test  cards  and  with  astigmatism  charts. 

Make  clear  the  fact  that  glare  depends  not  upon  the  intensity 
of  the  high  lights  but  upon  the  contrasts.  Have  students  collect 
information  about  light  conditions  in  local  establishments,  with 
reference  to  abundance  and  distribution  of  illumination,  presence  of 
flicker,  glare,  etc.  Have  students  collect  information  about  special 
dangers  to  eyes  in  local  establishments,  and  about  methods  of  guard- 
ing the  eyes.  Make  a  study  of  goggles  used  for  special  purposes. 

What  are  the  local  and  state  regulations  concerning  conditions 
inimical  to  people's  eyes  ?  Are  there  any  local  regulations  requiring 
the  administration  of  silver  nitrate  to  the  eyes  of  the  newborn  ? 
Give  statistical  data  as  to  the  prevalence,  increase,  or  decrease  of 
blindness  ;  preventive  and  remedial  measures. 

Demonstrate  the  administration  of  eye-drops  and  the  use  of  the 
eye-cup.  Show  how  a  foreign  body  is  to  be  removed. 

Demonstrate  the  proper  and  improper  placing  of  reading,  writ- 
ing, and  other  work  in  relation  to  illumination.  Point  out  the 
objection  to  illumination  of  work  by  direct  sunshine. 

References.  For  the  pupils:  HOUGH  and  SEDGWICK,  Human  Mecha- 
nism, pp.  395-401  ;  LEE,  Health  and  Disease,  chap.  vii.  For  the  teacher: 
PYLE,  Personal  Hygiene,  pp.  169-274. 

XLVI.    SOUND   SENSATIONS 

Have  some  students  report  on  the  methods  used  by  physicists 
for  determining  the  vibration  rates  for  light  and  sound  waves. 
Come  to  a  common-sense  conclusion  as  to  the  old  paradox  about 
there  being  no  sound  if  there  were  no  ears. 

Some  experiments  may  be  made  on  pitch  discrimination ;  and 
you  may  find  one  or  two  students  who  can  recognize  absolute 
pitch. 

Museum  and  demonstration  specimens  for  various  types  of 
sound-perceiving  organs.  Note  the  lateral  line  in  fishes,  the 
eardrum  in  the  cricket  and  locust,  and  so  on. 


64  MANUAL  FOR  TEACHERS 

Good  models  are  essential  for  the  study  of  ear  structure,  but 
good  charts  are  helpful.  It  is  not  worth  while,  however,  with  most 
classes,  to  give  much  time  to  the  detailed  study  of  structure. 

References.  For  the  pupils  :  HOUGH  and  SEDGWICK,  Human  Mechanism, 
pp.  258-262,  401-402  ;  STILES,  Human  Physiology,  pp.  143-148.  For  the 
teacher :  WATSON,  Behavior,  chaps,  xii,  xiii. 

XLVII.    RESPONSES   TO  GRAVITY 

Have  students  report  on  insects  and  other  animals  in  which 
they  may  have  had  an  opportunity  to  observe  evidence  of  response 
to  gravity,  including  balancing  and  righting  movements. 

Demonstrate  the  idea  of  the  statolith  with  a  covered  stender 
dish  containing  a  cork.  Show  with  blindfolded  students  that  we 
are  aware  of  our  posture  without  seeing  our  environment. 

With  the  frog  it  is  easy  to  demonstrate  compensatory  move- 
ments. Place  the  live  frog  in  a  glass  jar.  Tilt  the  jar  so  as  to 
bring  the  animal's  snout  down,  and  reverse.  Tilt  laterally.  Turn 
on  vertical  axis.  If  the  movements  are  properly  timed,  the 
responses  of  the  animal  are  immediate  and  striking.  It  is  possible 
to  show  that  these  movements  are  due  to  semicircular  canal 
reflexes  by  eliminating  the  function  of  the  eyes,  either  by  covering 
them  with  an  opaque  mixture  of  cotton,  vaseline,  and  lampblack, 
or  by  cutting  the  optic  nerves,  or  by  surrounding  the  jar  with 
a  large  piece  of  paper  or  cloth  that  offers  no  point  for  fixation. 
On  the  other  hand,  it  may  be  shown  that  many  of  these  responses 
arise  from  eye  reflexes,  by  destroying  the  semicircular  canals  or 
by  cutting  the  nerves  leading  from  them.  In  that  case,  however, 
there  remain  disturbances  in  locomotion,  showing  that  the  animal 
depends  upon  the  semicircular  canals  for  its  orientation  in  space. 

Have  students  make  comparative  tests  of  sensitiveness  of  hearing 
by  determining  the  distances  at  which  each  may  distinguish  the  tick- 
ing of  a  watch.  The  same  watch  will  of  course  be  used  in  all  the  tests. 

References.  For  the  pupils  :  HOUGH  and  SEDGWICK,  Human  Mecha- 
nism, pp.  262-263.  For  the  teacher :  WATSON,  Behavior,  chap.  xiv.  There 
will  be  numerous  reports  and  monographs  on  the  testing  of  candidates  for 
aerial  service,  giving  results  of  investigations  conducted  during  the  war. 


MANUAL  FOR  TEACHERS  65 

XLVIII.    INSTINCTS 

Have  students  note  examples  of  instincts  in  animals  and  in 
young  children  of  their  acquaintance,  and  then  attempt  to  analyze 
these  instincts,  so  far  as  possible,  in  terms  of  reflex  chains. 

Note  that  instincts,  like  reflexes,  cannot  be  perfect  in  the 
adaptive  sense. 

Have  students  make  note  of  variations  in  the  manifestations  of 
instincts  brought  about  by  changes  in  the  physiological  state  or 
by  the  concurrence  of  two  or  more  stimuli  leading  to  more 
or  less  conflict  between  responses. 

Have  students  report  experiences  with  animals,  or  from  their 
own  past,  in  which  instincts  were  modified,  either  through  the 
elimination  of  elements  or  through  the  formation  of  associations. 
All  sorts  of  learning  and  unlearning,  breaking  and  training,  in 
animals  and  in  very  young  children  would  furnish  illustrations. 

References.  For  the  pupils:  DARWIN,  Expression  of  the  Emotions; 
DARWIN,  Vegetable  Mold  and  Earthworms ;  FABRE,  The  Wonders  of 
Instinct ;  HOLMES,  Studies  in  Animal  Behavior,  chaps,  vi,  xi.  For  the 
teacher:  HOLMES,  Evolution  of  Animal  Intelligence,  chaps,  v,  vi ;  LOEB, 
Forced  Movements,  chap,  xviii ;  LOEB,  Comparative  Physiology  of  the 
Brain ;  LOEB,  The  Organism  as  a  Whole  ;  WATSON,  Behavior,  chaps,  iv-v. 

XLIX.    HABIT 

The  study  of  habit  should  culminate  in  effective  resolution.  It 
is  well  to  have  clearly  in  mind  the  mechanism  of  habit  formation, 
—  the  association  factor  and  the  short-circuiting  of  impulses  out 
of  the  cortex  into  the  spinal  cord ;  but  the  important  thing 
eventually  is  the  habit  of  habit-control. 

Have  students  give  striking  examples  of  habit  responses  (often 
humorous)  and  of  good  and  bad  habits.  Reports  on  experience 
in  training  lower  animals  ;  on  forming  and  breaking  habits  purpose- 
fully,—  from  observations  as  well  as  from  personal  experience, 
from  fiction  and  drama,  and  from  history  and  biography  or  other 
casual  reading. 

Get  examples  of  inhibitions  from  students'  experience  and 
observation. 


66  MANUAL  FOR  TEACHERS 

Study  the  relation  of  practice  to  habit  formation  and  the  measure- 
ment of  practice  effects,  —  for  example,  the  number  of  repetitions 
or  the  time  required  for  mastering  a  movement  (in  athletics,  in 
workmanship,  in  musical  performance,  etc.) ;  the  memorizing  of 
poetry  or  lines  in  a  play ;  the  mastery  of  mathematical  processes, 
penmanship,  drawing,  and  so  on.  Examples  of  arbitrary  associa- 
tions or  habits  are  found  in  learning  the  telegraph  instrument  and 
codes,  in  stenography,  in  typewriting,  in  cipher  codes,  and  so  on. 

Have  students  note  examples  of  routineers  among  young  persons, 
and  of  older  people  who  are  not  routineers.  Give  examples  of 
routine  that  could  be  replaced  by  other  equally  serviceable  routine 
for  the  sake  of  gratuitous  practice  in  changing  habits,  as  shifting 
keys  or  money  to  another  pocket,  rearranging  furniture  at  home, 
changing  route  to  school,  and  so  on. 

Consider  the  utility  and  the  dangers  of  habits. 

References.  JAMES,  Psychology  (Briefer  Course),  chap,  x;  HOLMES, 
Studies  in  Animal  Behavior,  chaps,  vii-ix ;  HOUGH  and  SEDGWICK, 
Human  Mechanism,  chap,  xviii ;  STILES,  Human  Physiology,  chap.  xii. 
For  the  teacher:  HOLMES,  Evolution  of  Animal  Intelligence,  chap,  vii ; 
LOEB,  Forced  Movements,  chap,  xix ;  WATSON,  Behavior,  chaps,  vi-ix. 

L.    CHEMICAL   INJURY   TO   THE   NERVOUS    SYSTEM 

Have  students  report  on  the  present  status  of  regulatory  laws 
pertaining  to  the  manufacture,  sale,  advertising,  and  labeling  of 
preparations  containing  alcohol  and  other  habit-forming  substances. 
A  comparison  of  labels  from  patent  medicines,  headache  cures,  etc.  is 
instructive.  Have  individual  reports  on  special  reading  assignments. 

The  subject  of  this  chapter  should  not  be  dismissed  without 
attention  being  called  to  the  advantages  that  the  race  has  derived 
from  an  understanding  of  the  physiological  effects  of  various 
alkaloids  and  synthetic  compounds.  A  report  on  the  contributions 
of  anesthetics  and  alkaloids  to  surgery  etc.  is  quite  as  important  as 
one  on  the  dangers  of  these  substances. 

References.  HOUGH  and  SEDGWICK,  Human  Mechanism,  pp.  376-377  ; 
LEE,  Health  and  Disease,  pp.  128-132.  In  encyclopedias,  articles  on 
anesthetics. 


MANUAL  FOR  TEACHERS  6? 

II.    UNITY  OF  LIFE 

This  study  should  consist  of  a  synthesis  of  all  significant  physio- 
logical ideas.  Have  students  make  lists  of  all  the  processes  or 
activities  that  are  common  to  several  different  organisms  specified, 
the  organisms  selected  representing  diverse  types  and  including 
plants  as  well  as  animals. 

For  each  process  or  activity,  have  students  describe  the  behavior 
of  the  organism  as  a  whole,  and  also  the  behavior  of  single  cells  of 
the  organism. 

For  each  process  or  activity,  have  students  compare  the  types  of 
organisms  selected ;  that  is,  point  out  similarities  and  differences. 

For  the  organism  as  a  whole,  show  the  interdependence  and 
coordination  of  processes;  no  part  has  meaning  except  in  its 
relations  to  all  the  others. 

References.  For  the  teacher:  CANNON,  Bodily  Changes,  chap,  xiv; 
CRILE,  Man  an  Adaptive  Mechanism;  LOEB,  The  Organism  as  a  Whole, 
chaps,  i,  xii ;  MORGAN,  Evolution  and  Adaptation,  chaps,  i,  iii,  x. 


PART  III.    THE  CONTINUITY  OF  LIFE 
LII.    GROWTH  AND  REGENERATION 

The  idea  of  the  varying  ratio  of  surface  and  volume  can  be 
made  clear  to  many  students  by  means  of  suitable  diagrams ;  but 
there  are  very  many  who  find  it  extremely  difficult,  or  even  im- 
possible, to  think  in  three  dimensions  from  data  supplied  by  figures 
in  one  plane ;  that  is,  figures  of  two  dimensions.  These  can  be 
helped  by  the  use  of  modeling  clay.  The  clay  is  first  cut  into 
cubes  of  the  same  size,  —  say  one  inch  or  one  centimeter.  The 
cubes  are  stacked  up  into  a  larger  mass,  and  the  superficial  area 
determined.  The  mass  is  successively  broken  down,  with  the 
resulting  increase  in  exposed  surface  made  obvious.  One-inch 
cubes  of  wood  may  be  used. 

While  the  idea  of  the  mathematical  limits  to  the  growth  of  a  cell 
should  be  clear,  it  should  not  be  emphasized  to  the  point  of  excluding 
the  idea  of  other  factors  operating  in  the  limitation  of  growth.  Current 
studies  on  the  relations  of  internal  secretions  to  the  regulation  of 
growth  and  form  are  constantly  throwing  new  light  on  the  subject. 

Have  regenerated  leaves,  starfish  and  Crustacea  with  regener- 
ated limbs,  specimens  of  knit  chicken  bones,  etc.  on  hand  for 
demonstration.  In  some  of  the  larger  cities  it  is  possible  to  obtain 
from  research  laboratories  or  from  museums  specimens  illustrating 
regeneration  in  vertebrates,  mollusks,  and  other  forms. 

Have  students  look  out  for  examples  of  pollarded  and  grafted 
trees,  and  for  newspaper  accounts  of  skin  and  bone  grafting,  or  trans- 
plantations of  organs.  Have  specimens  of  grafts  for  demonstration. 

References.  For  the  pupils :  BERGEN  and  CALDWELL,  Practical  Botany, 
pp.  82-89  ;  BERGEN  and  DAVIS,  Principles  of  Botany,  pp.  64-70;  COULTER, 
BARNES,  and  COWLES,  Textbook  of  Botany,  pp.  417-426;  DUGGAR,  Plant 
Physiology,  chap.  xiii.  For  the  teacher:  DAVENPORT,  Principles  of  Breed- 
ing, pp.  316-338  ;  LOEB,  The  Organism  as  a  Whole,  chap,  vii ;  MORGAN, 
Experimental  Zoology,  chaps,  xv-xxii. 

68 


MANUAL  FOR  TEACHERS  69 

LIII.    DEVELOPMENT 

In  the  spring  it  is  possible  to  have  live  frogs'  eggs  in  dishes, 
and  to  watch  their  development  under  the  microscope  and 
magnifying  glasses. 

A  series  of  models  showing  the  development  of  Amphioxus 
(fifteen  to  twenty  stages)  is  helpful.  In  the  absence  of  models, 
charts  may  be  used. 

Have  preparations  and  models  showing  the  development  of 
different  types  of  insects,  a  fish,  a  frog,  a  bird  (chick),  and  a 
mammal  (sheep  or  rabbit).  Eggs  and  cocoons  of  various  local 
insects,  also  mealworms  and  other  insect  larvae,  should  be  examined 
alive.  If  possible,  the  emergence  of  the  animals  from  the  resting 
stage  (egg  or  pupa)  should  be  observed  in  the  classroom  by  the 
students.  In  some  localities  it  should  be  possible  to  visit  incubators 
or  henneries,  to  see  the  chicks  come  out  of  the  shell.  Along  the 
shore,  shedder  crabs  and  the  molting  of  many  animals  may  be 
observed.  Caterpillars  in  the  process  of  pupation  may  be  studied 
in  the  laboratory.  From  spring  to  late  summer  (from  April  to 
September  for  most  parts  of  the  country)  it  is  possible  to  get 
complete  life  histories  of  mosquitoes  by  exposing  tumblers  of 
water  on  warm  evenings ;  the  female  mosquitoes  will  deposit  their 
eggs,  and  the  development  may  then  be  watched  in  the  laboratory, 
under  a  reading  glass.  Cover  the  tumblers  with  cheesecloth,  to 
prevent  the  escape  of  the  adults. 

Under  favorable  conditions  the  development  of  the  frog  and  the 
early  stages  of  fishes  can  be  followed  in  the  laboratory.  If  possible, 
excursions  to  fisheries  and  to  field  should  be  made  for  the  study 
of  the  stages  in  animal  development. 

If  goldfish  are  kept  in  the  laboratory  or  stock-room,  one  can 
manage  to  get  fresh  segmentation  stages  late  in  the  winter  and  in 
the  early  spring.  The  animals  are  fed  up  in  the  winter;  at  the 
beginning  of  the  breeding  season  the  fish  are  isolated  in  large 
battery  jars,  and  then  "  stripped "  into  shallow  glass  vessels. 

Incubators  for  bacteriological  work  with  thermostats  can  be 
used  for  the  incubation  of  hens'  eggs  (104°  F.).  You  must  make 


70  MANUAL  FOR  TEACHERS 

sure  that  the  eggs  are  fertilized ;  it  is  best  to  purchase  from  poultry 
specialists,  and  to  examine  them  by  holding  up  to  light  after  three 
or  four  days. 

References.  Special  reports  on  life  histories  of  various  insects  and 
batrachians;  MITCHELL,  CHALMERS,  The  Childhood  of  Animals,  chap.  ii. 
For  the  teacher :  CONKLIN,  Heredity  and  Environment  in  the  Develop- 
ment of  Man,  chap,  i,  pp.  179-187  ;  DAVENPORT,  Principles  of  Breeding, 
chap,  vii,  pp.  336-344 ;  KELLICOTT,  General  Embryology,  chaps,  i,  ii. 

LIV.    CONDITIONS  FOR  DEVELOPMENT 

It  is  very  difficult  for  most  people  to  separate  in  their  minds 
the  facts  of  growth  from  the  facts  of  development.  Call  attention 
to  diversities  in  size  among  the  members  of  the  class ;  then  have 
the  students  decide  whether  size  is  always  and  everywhere  directly 
correlated  with  maturity ;  that  is,'  whether  growth  (in  size)  has 
always  been  identical  with  or  even  parallel  with  development. 
Nevertheless,  conditions  that  are  unfavorable  to  growth  are  likely 
to  be  unfavorable  to  development ;  ordinarily  growth  furnishes  the 
material  basis  for  development. 

For  a  comparison  of  different  conditions,  concentrations,  etc., 
in  relation  to  growth  of  yeast,  use  fermentation  tubes  (Fig.  n). 

Instances  of  malnutrition  reacting  upon  development  are  to  be 
found  in  nearly  every  community.  Malformations  and  monstrosi- 
ties of  various  kinds  are  referred  to  in  books  and  in  current  litera- 
ture. Consider  the  effects  of  early  neglect,  of  foot-binding,  etc. 

References.  For  the  teacher  :  AYRES,  Laggards  in  our  Schools,  chap,  xi ; 
DAVENPORT,  Principles  of  Breeding,  chap,  ix ;  MANGOLD,  Problems  of 
Child  Welfare,  Part  I,  chap,  iii  and  Part  II,  chap,  i ;  MORGAN,  Experimental 
Zoology,  chaps,  ii-iii.  Publications  of  the  United  States  Children's  Bureau. 

LV.    NEW  ORGANISMS 

Show  yeast  cells  under  the  microscope  for  the  buds.  Fresh 
material  (in  dilute  molasses)  is  necessary.  To  show  the  spore 
formation,  use  preparations  from  an  older  culture ;  that  is,  one 
from  which  the  food  has  been  exhausted, 


MANUAL  FOR  TEACHERS 


Have  students  make  experiments  on  the  distribution  of  mold 
and  yeast  spores.  Thin  slices  of  bread  exposed  under  various 
conditions  or  in  different  localities  (or  directly  inoculated  with  dust) 
and  placed  in  moist  chambers  will  serve 
as  media  for  the  molds.  For  moist  chamber 
a  tumbler  inverted  over  a  few  thicknesses 
of  wet  filter-paper  or  blotter  will  do.  For 
the  yeasts,  fruit  juices  or  sirup  diluted 
(a  teaspoonful  to  the  pint),  or  weak  cider, 
exposed  in  test  tubes,  which  are  then 
closed  with  plugs  of  cotton. 

Study  spores  of  molds  under  the  micro- 
scope. Mildews,  rusts,  mosses,  ferns,  and 
other  plants  should  be  drawn  upon  for 
specimens  of  spores.  Many  kinds  of  spores, 
including  pollen  grains,  can  be  made  to 
germinate  by  placing  them  in  a  drop  of 
dilute  sugar  solution  on  a  microscopic 
slide  in  a  moist  chamber.  Germinate  fern 
and  moss  spores  on  moist  earth  under 
glass.  Sporangia  should  also  be  seen. 

References.  Special  reports  on  spore  for- 
mation etc.  in  various  plants.  HOLMES,  Animal 
Biology,  chap,  xxvii;  OSTERHOUT,  Experi- 
ments with  Plants,  chap.  ix.  For  the  teacher : 
COULTER,  BARNES,  and  COWLES,  Textbook  of 
Botany,  pp.  805-816;  PARKER  and  HASWELL, 
Zoology. 


FIG.  n.   Fermentation 
Tube 

Fill  the  tube  completely  with 
the  nutritive  fluid.  Insert  the 
yeast  or  culture  into  the  low- 
est part  of  the  bend,  using  a 
pipette.  Close  the  mouth  with 
cotton.  The  accumulation  of 
gas  in  the  highest  part  of  the 
tube  is  both  an  indication  and  a 
measure  of  fermentation.  The 
bulb  should  be  only  partially 
filled,  to  leave  space  for  the 
liquid  displaced  from  the  tube 


LVI.    SEX 

Favorable  paramecium  cultures  show 

conjugation  almost  constantly  ;  and  if  it  is  at  all  possible  to  manage 
it,  the  students  should  see  the  process  under  the  microscope. 

Conjugating  spirogyra  can  be  found  late  in  the  summer  and  in 
the  fall,  by  collecting  very  early  in  the  morning.  Strings  of  ladders 
and  zygotes  can  be  preserved  in  formalin  (2  per  cent  to  3  per  cent) 
or  mounted  in  glycerin  for  microscopic  demonstrations. 


72  MANUAL  FOR  TEACHERS 

Most  of  the  colleges  and  experiment  stations  keep  cultures 
of  molds  that  will  enable  you  to  obtain  zygote  formation  in  the 
laboratory. 

Gametes  of  rockweed  and  other  algae  are  best  studied  from 
charts,  except  at  the  seacoast,  where  fresh  material  is  available 
early  in  the  spring. 

References.  For  the  teacher:  COULTER,  Evolution  of  Sex  in  Plants; 
COULTER,  BARNES,  and  COWLES,  Textbook  of  Botany,  pp.  816-824,  878- 
904;  GALLOWAY,  Biology  of  Sex;  GEDDES  and  THOMSON,  Sex;  MORGAN, 
Heredity  and  Sex,  chap.  i. 

LVII.    FLOWERS 

Where  it  is  possible  to  have  tulips  for  the  first  flower,  they  will 
be  found  very  useful.  Two  students  can  easily  work  on  one  flower 
without  mutilating  it,  and  only  a  few  need  to  be  dissected  for  a 
whole  class.  They  will  keep  so  that  successive  classes  may  use 
the  same  material.  In  many  cases  it  would  be  no  more  expensive 
to  have  tulips  than  some  other  flowers.  Whatever  flower  is  taken 
first  should  be  regular,  symmetrical,  and  perfect.  Later  other  forms 
may  be  profitably  studied.  Flower  models  are  helpful  in  class  dis- 
cussions, demonstrations,  and  recitations,  as  well  as  for  compari- 
sons of  types  that  blossom  at  different  seasons  of  the  year.  There 
should  also  be  available  an  abundance  of  charts. 

For  pollen-tube  demonstration,  put  pollen  of  various  flowers  in 
drops  of  dilute  sugar  solution  on  microscope  slides ;  keep  in  moist 
chamber  overnight ;  examine  with  microscope  under  cover  glass. 

Slices  of  larger  ovaries  may  be  mounted  on  glass  slides  and 
examined  with  magnifying  glasses ;  if  they  are  to  be  kept  for 
some  time,  place  in  glycerin. 

Fertilization  in  flowers  can  best  be  explained  with  the  help  of  a 
blackboard  diagram  that  is  built  up  and  changed  with  the  progress 
of  the  description. 

References.  ANDREWS,  Practical  Course,  pp.  196-223 ;  BERGEN  and 
CALDWELL,  Practical  Botany,  pp.  20-23 ;  BERGEN  and  DAVIS,  Principles 
of  Botany,  chap,  xiii,  pp.  138-145;  COULTER,  Plant  Life  and  Plant  Uses, 
pp.  258-301  ;  OSTERHOUT,  Experiments,  chap.  vi.  For  the  teacher: 
COULTER,  BARNES,  and  COWLES,  Textbook,  pp.  825-834. 


MANUAL  FOR  TEACHERS  73 

LVIII.    POLLENATION  -  LIX.  ADAPTATIONS   OF  FLOWERS 

Flowers  may  be  brought  to  the  laboratory  for  examination  as 
to  the  mechanism  of  pollen  discharge.  Get  flowers  of  grasses, 
willows,  oaks,  poplars,  maples,  etc.,  as  well  as  those  with  conspicu- 
ous corollas.  The  structure  of  the  bumblebees,  honeybees,  and 
other  pollenating  insects  should  be  studied  in  this  connection. 

Field  trips  for  the  study  of  insect  visits  to  flowers  are  most 
interesting  and  valuable.  Have  the  students  find  the  pollen  car- 
riers for  some  of  the  common  wild  and  cultivated  plants.  What 
insects  visit  more  than  one  kind  of  flower?  What  flowers  are 
visited  by  more  than  one  kind  of  insect  ?  Are  the  visits  of  mutual 
advantage  in  all  cases  ? 

Have  students  find  out  what  evidence  there  is  that  the  wind 
brings  pollen  over  a  considerable  distance.  In  regions  cultivat- 
ing pedigreed  grains  and  corn,  farmers  often  have  to  construct 
windbreaks  to  prevent  foreign  pollen  from  crossing  with  their  special 
varieties.  Hybrid  willows  and  other  species  of  wind-pollenated 
trees  are  evidence  of  such  crossing. 

Study  two  or  three  species  of  zygomorphic  flowers  that  are 
dependent  upon  insects,  and  one  or  two  that  are  self-pollenating. 
Visit  gardens  and  greenhouses. 

Assign  special  readings  and  reports  on  extrafloral  nectaries,  on 
specific  insect-flower  relations,  on  economic  aspects  of  the  relation, 
and  on  cleistogamous  flowers. 

References.  ANDREWS,  Practical  Course,  pp.  235-249;  BERGEN  and 
DAVIS,  Principles,  chap,  xxxii;  COULTER,  Plant  Life,  pp.  301-324;  DARWIN, 
Forms  of  Flowers.  For  the  teacher:  COULTER,  BARNES,  and  COWLES,  Text- 
book, pp.  834-878  ;  MORGAN,  Evolution  and  Adaptation,  chap.  i. 

LX.    FRUIT  AND   SEED   DISTRIBUTION 

Dried  fruits  of  many  different  species  are  easily  kept  in  boxes 
and  may  be  used  over  and  over  again,  although  the  collection 
should  be  constantly  supplemented  and  enlarged  by  new  additions. 
Present  materials  in  ecological  relations ;  that  is,  in  accordance 
with  the  agency  of  distribution  or  the  type  of  seed  protection. 


74  MANUAL  FOR  TEACHERS 

Field  studies  along  roadsides,  vacant  lots,  and  the  woods  will  fur- 
nish abundant  illustrative  material  and  opportunity  for  collecting. 

References.  ANDREWS,  Practical  Course,  chap,  viii ;  BERGEN  and  DAVIS, 
Principles,  chaps,  xvi,  xxxiii ;  COULTER,  Plant  Life,  chap,  viii ;  OSTERHOUT, 
Experiments,  chap,  vii ;  Farmers'  Bulletins.  For  the  teacher :  COULTER, 
BARNES,  and  COWLES,  pp.  904-929. 

LXI.  ALTERNATION  OF  GENERATIONS 

Use  fresh  or  dried  moss  plants  (the  pigeon-wheat  moss,  Poly- 
trichum,  is  good  and  found  almost  everywhere)  showing  both 
gametophytes  and  sporophytes.  Students  should  see  archegonia 
and  antheridia  through  the  microscope,  but  good  blackboard  draw- 
ings or  charts  are  necessary  for  satisfactory  study. 

Fern  prothalli  can  be  grown  by  sprinkling  the  spores  on  moist 
earth  placed  in  dishes,  covered  with  glass  and  kept  at  room  tem- 
perature. Show  archegonia  and  antheridia  through  microscope. 

Hydromedusae  are  best  studied  in  small  vials  with  the  magnify- 
ing glasses.  Thus  preserved,  the  specimens  will  keep  indefinitely. 

References.  BERGEN  and  DAVIS,  Principles,  chaps,  xxiv-xxix ;  COULTER, 
Plant  Life,  pp.  401-403.  For  the  teacher:  COULTER,  Evolution  of  Sex  in 
Plants ;  COULTER,  BARNES,  and  COWLES,  pp.  92,  264-268,  805-824. 

LXII.    REPRODUCTION  IN  ANIMALS 

This  subject  does  not  lend  itself  readily  to  laboratory  or  field 
study  by  young  people ;  nor  is  it  always  feasible  to  discuss  it  in 
class,  especially  in  mixed  schools. 

Where  it  is  not  feasible  to  keep  live  fish  (see  p.  69),  it  may 
be  possible  to  arrange  for  visits  to  an  aquarium  or  to  a  fish  station, 
where  the  students  may  see  roe  and  milt,  and  where  they  may  see 
a  demonstration  of  "  stripping  "  and  artificial  fertilization. 

There  is  a  great  deal  of  interesting  reading  on  the  breeding 
habits  of  common  animals,  to  which  students  should  be  referred, 
even  if  there  is  no  class  discussion  of  results. 

References.  Special  reports  on  habits  of  birds,  fishes,  and  other 
animal  groups. 


MANUAL  FOR  TEACHERS  75 


LXIII.    INFANCY  AND  PARENTAL  CARE 

This  is  a  review  study  of  the  whole  subject  of  reproduction,  with 
emphasis  upon  the  relation  between  parent  and  offspring,  and  of 
the  two  to  the  species.  This  may  be  correlated  with  historical  and 
ethnological  studies,  as  well  as  with  social  science  and  community 
civics.  Have  students  prepare  diagrams  showing  the  increasing 
dependence  of  spores,  gametes,  and  zygotes  upon  the  parent,  in 
series  of  plants  or  of  animals.  Charts  giving  a  general  view  of 
the  plant  and  animal  systems  are  helpful  in  this  connection,  even 
if  no  attempt  has  as  yet  been  made  to  study  classification.  See 
Chapters  LXXXVI  and  LXXXVII  of  the  text. 

Guard  against  the  interpretation  of  phenomena  in  terms  of 
"  purpose." 

References.  MITCHELL,  The  Childhood  of  Animals,  especially  chaps,  i, 
Hi,  iv;  PYCRAFT,  The  Infancy  of  Animals;  BURBANK,  Training  of  the 
Human  Plant ;  FISKE,  The  Prolongation  of  Youth. 


PART    IV.     ORGANISMS   IN  THEIR   EXTERNAL 
RELATIONS 

LXIV.    OBSTACLES   TO  LIFE 

Earlier  experiments  have  already  demonstrated  the  influence  of 
external  forces  upon  growth  and  upon  development.  This  chapter 
is  in  the  nature  of  a  summary  with  a  view  to  a  new  departure. 

Have  students  make  (in  the  form  of  a  table)  a  list  of  ten 
familiar  plants  and  ten  familiar  animals,  with  a  note  on  the  char- 
acteristic appearance  or  behavior  (a)  at  high  temperatures  (sum- 
mer) and  (b)  at  low  temperatures  (winter). 

Have  students  state  experiences  with  frostbite,  frozen  ear,  etc., 
,with  frozen  snakes  or  fish,  and  so  on.  Why  is  freezing  of  proto- 
plasm reversible,  whereas  the  effect  of  heat  is  irreversible  ?  What 
are  the  dangers  of  natural  ice?  What  is  the  object  of  cooling 
milk  immediately  after  taking  it  from  the  cow  ?  What  is  the 
object  of  keeping  milk  and  other  food  at  low  temperatures?  What 
is  the  use  of  pasteurizing  milk,  and  how  is  it  accomplished? 
What  is  the  objection  to  boiling  milk  ? 

In  discussing  the  effect  of  water  shortage  or  excess,  point  out 
that  some  of  the  characteristic  summer  and  winter  conditions  of 
plants  and  animals  are  due  to  the  water  relation.  What  practical 
use  is  made  of  the  fact  that  protoplasm  cannot  be  active  without 
water  ?  What  practical  methods  are  employed  for  excluding  water 
from  materials  that  might  otherwise  be  destroyed  by  bacteria, 
molds,  or  yeast  ? 

If  the  influence  of  light  upon  growth  has  not  been  demonstrated 
earlier,  it  should  now  be  shown  with  bacteria  cultures  in  petri 
dishes.  Cover  a  portion  of  each  dish  with  black  paper ;  or  cover 
the  whole  dish  and  cut  distinctive  holes  or  letters  in  the  paper,  to 
admit  light.  After  exposing  the  sterilized  medium  to  infection,  the 
covers  are  put  on  and  the  dishes  are  exposed  to  strong  sunlight 

76 


MANUAL  FOR  TEACHERS  77 

at  room  temperature  or  warmer;  later  they  are  examined  for 
bacterial  growth,  showing  different  behavior  in  light  and  darkness. 

What  practical  use  can  be  made  of  the  fact  that  light  is  injurious 
to  protoplasm  (as  in  bacteria)  ?  Refer  to  the  use  of  ultraviolet 
rays  for  the  sterilization  of  water  supplies  and  other  food  materials. 
Have  students  make  special  reports. 

What  practical  use  is  made  of  the  fact  that  many  salts  (chemi- 
cals) are  injurious  to  living  things  ?  Refer  to  the  use  of  salt  or 
ashes  on  the  ground  for  killing  weeds.  In  the  use  of  salt  (and 
sugar)  for  preserving  food,  part  of  the  effect  is  no  doubt  due  to 
the  drying.  Compare  the  drought  characteristics  of  many  swamp 
plants,  such  as  the  mangrove. 

References.  For  the  pupils  :  COULTER,  BARNES,  and  COWLES,  Textbook 
of  Botany,  pp.  565-589,  704-718;  DARWIN,  Origin  of  Species,  chap,  iii; 
JORDAN  and  KELLOGG,  Evolution  and  Animal  Life,  chap.  iii.  For  the 
teacher:  MORGAN,  Experimental  Zoology,  chap.  ii. 

LXV.    THE  CONFLICT  OF  LIFE  WITH  LIFE 

Most  of  the  ideas  in  this  chapter  deal  with  abstractions  that 
cannot  be  illustrated  or  demonstrated  directly,  —  as  predation, 
parasitism,  competition,  or  struggle.  But  these  ideas  can  be  easily 
formed  from  familiar  examples. 

Have  specimens  of  tapeworm  and  microscopic  preparations  and 
pictures  of  roundworm,  hookworm,  and  other  parasites. 

Students  can  suggest  many  examples  of  predatory  and  parasitic  re- 
lations, and  comprehensive  lists  can  be  compiled  from  their  reports. 

Selective  and  nonselective  elimination  should  offer  no  difficulty ; 
examples  abound  on  every  side,  in  human  affairs  as  well  as  in  those 
of  the  common  animals  and  plants.  The  important  thing  is  to  make 
clear  the  metaphorical  sense  in  which  the  word  struggle  is  used,  and 
to  form  connotations  that  avoid  the  banal  element  of  competition. 

References.  BERGEN  and  CALDWELL,  Practical  Botany,  chap,  xxi ; 
BERGEN  and  DAVIS,  Principles,  chap,  xxx ;  DARWIN,  Origin,  chap,  iv ; 
EALAND,  Insects  and  Man,  chap,  vii;  HODGE  and  DAWSON,  Civic  Biology, 
chaps,  xviii,  xx,  xxiv;  JORDAN  and  KELLOGG,  Evolution  and  Animal 
Life,  chaps,  v,  xvii.  For  the  teacher:  MORGAN,  Evolution  and  Adaptation, 
chaps,  iv,  v ;  MORGAN,  Experimental  Zoology,  chap.  xiii. 


78  MANUAL  FOR  TEACHERS 


LXVI.    PROTECTIVE  ARMORS   OF  ORGANISMS 

It  is  not  worth  while  to  study  skin  structures  of  plants  and 
animals  in  detail.  Illustrative  specimens  should  be  on  hand,  and 
visits  to  museums,  gardens,  menageries,  aquaria,  etc.  encouraged. 

The  general  ideas  discussed  are  simple  enough  and  should  not 
take  too  much  time  beyond  the  reading  and  summarizing  in  note- 
books, with  perhaps  additional  examples. 

References.  BERGEN  and  DAVIS,  Principles,  chap,  xxxi;  COULTER, 
BARNES,  and  COWLES,  Textbook,  pp.  741-744. 


LXVII.    PROTECTIVE  PIGMENTS   AND  APPEARANCES 

That  colors,  patterns,  etc.  may  protect  is  obvious  enough.  More 
difficult,  and  perhaps  more  important,  is  the  idea  that  the  resem- 
blances etc.  may  be  quite  fortuitous  and  without  practical  signifi- 
cance either  in  the  lives  of  the  organisms  or  in  the  evolution  of 
species.  Have  prepared  specimens  to  illustrate  protective  colora- 
tion, warning  coloration,  and  mimicry ;  have  museum  studies  and 
encourage  students  to  bring  in  specimens  found  afield. 

What  experiences  have  the  students  had  with  sunburn  and  tan  ? 
Refer  to  Cunningham's  experiment  with  flatfish. 

What  experiences  have  the  students  had  with  the  behavior  of 
animals  that  show  dependence  upon  the  coloration  etc.  ? 

Have  cactus  and  other  xerophytic  plants  to  illustrate  reduction 
of  surface  as  an  adaptation.  Get  some  students  to  experiment  on 
whether  the  drought  brings  about  the  reduction  of  surface,  as  a 
modification  during  development,  or  whether  these  plants  are 
incapable  of  living  where  there  is  a  relative  excess  of  water. 

References.  For  the  pupils :  DAVENPORT,  Elements  of  Zoology,  pp.  35-38  ; 
JORDAN  and  KELLOGG,  Evolution  and  Animal  Life,  chap,  xix ;  KELLOGG, 
American  Insects,  chap,  xvii;  POULTON,  The  Colors  of  Animals;  WAL- 
LACE, Natural  Selection  and  Tropical  Nature,  chap.  v.  For  the  teacher: 
MORGAN,  Evolution  and  Adaptation,  pp.  357-360. 


MANUAL  FOR  TEACHERS  79 

LXVIII.    PROTECTIVE  MOVEMENTS  —  LXIX.    PROTECTIVE 
ACTIVITIES 

Have  students  handle  live  animals  of  various  kinds,  in  the 
aquarium  and  in  the  vivarium  at  school  or  wherever  they  can 
outside,  and  report  the  contracting  and  flight  movements.  Many 
of  these  movements  are  already  familiar  enough,  and  too  much 
time  should  not  be  taken  for  their  consideration  in  the  classroom. 
"  Playing  possum "  is  a  widespread  reaction ;  point  out  that  it 
is  a  general  reaction  that  may  or  may  not  be  useful,  and  that 
may  or  may  not  be  related  to  the  advantage  of  the  species. 

Have  specimens  of  fence  lizards  and  other  chameleons,  and 
note  color  changes  in  other  reptiles,  in  batrachians,  and  in  fishes. 

Where  there  is  opportunity  the  students  that  take  an  interest 
in  morphology  may  be  encouraged  to  study  homologies  and 
analogies  in  animal  appendages.  Individual  students  might  pre- 
pare mounted  series  of  crustacean  or  insect  appendages  and 
mouth-parts. 

Special  reports  on  bird  and  fish  migrations  should  include  results 
of  field  observations  as  well  as  of  reading. 

Laboratory  and  field  studies  of  burrowing  worms  and  insect 
larvae,  and  of  birds'  nests. 

Charts  and  microscopic  demonstration  of  nettling  cells. 

Study  of  leaf-scars  to  show  self-healing  surface;  microscopic 
preparation  of  the  scission  layer. 

Encourage  students  to  collect  insect  galls  and  to  find  out  what 
insects  cause  them  on  common  plants. 

Have  special  reports  made  on  field  observations  and  readings 
on  the  homing  habits  of  animals,  from  the  point  of  view  of 
protection. 

References.  COULTER,  J.  G.,  Plant  Life  and  Plant  Uses,  pp.  242-247; 
COULTER,  BARNES,  and  COWLES,  Textbook,  pp.  354,  582-588 ;  OSTER- 
HOUT,  Experiments,  pp.  212-215,  332.  For  the  teacher:  MORGAN,  Experi- 
mental Zoology,  chap.  xvi. 


8o 


MANUAL  FOR  TEACHERS 


LXX.    THE  FOREST  IN  RELATION  TO  MAN 

The  forest  has  for  a  long  time  been  the  favorite  hook  upon  which 
to  hang  the  sermon  of  conservation,  since  it  lends  itself  admirably 
to  the  purpose,  both  for  economic  reasons  and  for  biological  ones. 


FIG.  12 

The  slope  consists  of  a  wooden  frame,  supported  at  an  angle  of  about  45  degrees, 
inclosing  a  pane  of  glass  with  a  trough  at  the  bottom  leading  to  a  small  drain-hole 
at  the  end.  The  most  convenient  size  is  that  of  the  large  blotters  used  on  desks  or 
in  desk  pads.  Two  beakers,  two  cylinders,  preferably  graduated,  a  florist's  spray,  and 
a  supply  of  water  complete  the  equipment.  Equal  quantities  of  water  are  placed  in 
the  cylinders  or  graduates.  The  water  from  one  of  these  is  drawn  into  the  bulb  of 
the  spray  and  rained  first  upon  the  bare  glass,  representing  a  deforested  mountain 
side,  and  then  upon  the  slope  covered  with  two  blotters,  one  representing  the  forest 
trees  and  the  other  representing  the  forest  floor,  or  duff.  In  each  case  as  much 
water  as  possible  is  collected  in  the  beaker  and  returned  to  the  respective  cylinders 
for  comparison.  The  water  can  be  seen  across  the  schoolroom  more  easily  if  it  is 
slightly  colored,  as  with  a  few  drops  of  red  ink.  (Apparatus  designed  for  use  in  the 
Department  of  Public  Education  of  the  American  Museum  of  Natural  History  by 
George  H.  Sherwood,  Curator) 

This  subject  is  perhaps  best  studied  in  connection  with  Arbor 
Day  observance.  Special  reports  on  various  aspects  of  the  forest 
in  relation  to  human  welfare  furnish  the  best  means  of  arousing 
interest  and  impressing  the  students  with  the  far-reaching  contacts 


MANUAL  FOR  TEACHERS  8 1 

between  the  forest  and  human  affairs.  These  reports  may  take 
the  form  of  statistical  reports  on  such  topics  as  the  quantities  or 
values  of  various  forest  products ;  water  supply,  navigation,  water 
power ;  soil  erosion ;  harbor  maintenance ;  Value  of  improved  lum- 
bering methods;  injurious  species  of  insects  and  fungi,  and  specific 
methods  of  control ;  the  birds  in  relation  to  the  forest ;  danger  of 
fire  and  the  prevention  of  fire ;  relative  values  of  different  kinds  of 
wood  ;  different  rates  of  growth ;  methods  of  reforesting ;  special 
services  of  state  and  federal  bureaus ;  recent  legislation ;  etc. 

The  effect  of  clearing  upon  soil  erosion,  floods,  etc.  is  often 
demonstrated  by  means  of  the  model  illustrated  in  Fig.  12.  This 
demonstration  does  not,  of  course,  prove  that  the  forest  retains 
water  longer  than  does  the  nude  soil ;  it  only  helps  to  visualize  the 
relationships  between  the  two  kinds  of  hillside  and  the  run-off. 

References.  BERGEN  and  '  CALDWELL,  Practical  Botany,  chap,  xxii ; 
COULTER,  J.  G.,  Plant  Life,  pp.  195-200;  HODGE  and  DAWSON,  Civic 
Biology,  chap,  vi ;  MOON,  The  Book  of  Forestry ;  ROGERS,  The  Tree 
Book.  Yearbooks  of  the  United  States  Department  of  Agriculture ;  re- 
ports and  bulletins  of  the  United  States  bureau  of  Forestry;  bulletins 
and  reports  of  state  departments  of  agriculture ;  United  States  Depart- 
ment of  State,  publications  on  forest  reserves  and  recreation. 

LXXI.    BACTERIA  AND  HEALTH  -  LXXII.    CONTROL  AND 
USE  OF  BACTERIA 

The  subject  matter  here  is  largely  in  the  nature  of  a  new 
synthesis  of  material  that  is  for  the  most  part  already  familiar. 

The  destruction  of  bacteria  discharged  from  diseased  persons, 
and  the  prevention  of  infections,  are  the  practical  problems  sug- 
gested. Various  methods,  materials,  and  regulations  directed  to 
these  ends  should  be  correlated  with  the  data  given  in  the  table 
on  page  387.  Have  specimens  of  the  germicides  to  be  used  in 
various  situations ;  and  perhaps  make  comparative  studies  of  their 
effectiveness  with  petri-dish  cultures.  An  interesting  experiment 
in  connection  with  this  study  is  to  obtain  cultures  from  a  mouth- 
rinsing  thrown  into  a  petri  dish,  and  then  a  similar  rinsing  after 
the  use  of  a  commercial  mouth  wash. 


82  MANUAL  FOR  TEACHERS 

Special  reports  on  methods  and  regulations  in  hospitals  and 
sickrooms  are  interesting  and  valuable. 

Typhoid  carriers  are  presented  to  the  public  attention  from  time 
to  time ;  local  and  current  references  are  more  interesting  than 
remote  cases. 

Special  studies  may  be  made  of  local  conditions  and  current 
activities  in  the  way  of  legislation  and  administrative  regulation, 
with  reference  to  the  various  items  mentioned  in  the  latter  part 
of  Chapter  LXXI  and  in  section  434  of  Chapter  LXXII,  and  with 
reference  to  markets,  cold-storage  plants,  etc. 

Analyze  city  or  state  health  department  reports  of  morbidity 
and  mortality. 

For  the  economic  aspects,  reports  upon  accessible  industries  men- 
tioned in  the  text,  or  other  local  activities  in  which  microorganisms  play 
a  part,  and  the  collection  of  commercial  products  or  specimens  illus- 
trating processes,  should  be  encouraged.  Have  demonstrations  of  such 
specimens  in  class,  and,  in  some  cases,  of  actual  processes,  as  the 
souring  of  vinegar  and  the  rotting  of  flax  or  of  sponges. 

References.  BUCHANAN,  Household  Bacteriology ;  CONN,  Agricultural 
Bacteriology ;  HODGE  and  DAWSON,  Civic  Biology,  chaps,  xxi-xxiii ; 
HOLMES,  Animal  Biology,  chap,  xxxvi ;  JORDAN,  Textbook  of  General 
Bacteriology,  chap,  xxxiv ;  LIPMAN,  Bacteria  in  Relation  to  Country  Life, 
chaps,  i,  xxxvi-xlix ;  LOCY,  Biology  and  its  Makers,  chap.  xiii.  Bulletins 
and  reports  of  the  local  and  state  departments  of  health  and  of  the  United 
States  Public  Health  Service.  For  the  teacher:  CHAPIN,  Sources  and 
Modes  of  Infection ;  JORDAN,  Textbook  of  General  Bacteriology,  chaps,  i, 
v,  xxii,  xxxiv. 

LXXIII.    INSECTS  AS   SPREADERS   OF  DISEASE 

Prepare  a  number  of  petri  dishes  with  nutrient  agar  or  gelatin. 
Have  students  bring  in  flies  caught  in  various  parts  of  town  and 
in  various  situations.  Place  a  fly  in  each  dish,  after  clipping  off 
the  wings,  and  keep  in  a  warm  place  for  two  or  three  days.  Do 
not  omit  several  control  dishes.  Have  students  summarize  results 
in  tabular  form. 

Have  surveys  made  of  various  parts  of  town  accessible  to  the 
students,  to  find  out  the  relative  prevalence  of  flies  (especially  in 


MANUAL  FOR  TEACHERS  83 

relation  to  food  markets)  and  the  distribution  of  breeding  places. 
Where  the  flies  have  not  been  virtually  exterminated  through  the 
efforts  of  the  community,  it  is  legitimate  to  undertake  a  systematic 
campaign,  in  cooperation  with  official  bodies  and  civic  organiza- 
tions. Where  the  fly  is  no  longer  a  pest,  this  study  has  only 
a  historical  interest ;  but  the  history  is  so  recent  that  it  is  worth 
impressing  as  an  example  of  man's  control  of  his  environment. 

References.  CHAPIN,  Sources  and  Modes  of  Infection,  pp.  417-447; 
EALAND,  Insects  and  Man,  pp.  119-136;  HODGE  and  DAWSON,  Civic 
Biology,  chap,  x ;  KELLOGG  and  DOANE,  Economic  Zoology,  pp.  377-384  ; 
KELLOGG  and  DOANE,  Insects  and  Disease;  RILEY  and  JOHANNSEN, 
Handbook  of  Medical  Entomology,  chap.  v.  Bulletins  and  reports  of  local 
and  state  departments  of  health;  bulletins  of  the  United  States  Public 
Health  Service  and  of  the  United  States  Department  of  Agriculture. 

LXXIV.    INSECTS  AS  INTERMEDIATE  HOSTS 

Get  first  a  quantitative  idea  of  the  prevalence  of  malaria  (or 
yellow  fever ! )  in  the  locality.  Students  should  set  out  to  find 
possible  breeding  places  for  mosquitoes,  and  chart  their  distribu- 
tion. Study  local  operations  directed  toward  the  extermination 
of  mosquitoes. 

Have  special  reports  on  the  sanitary  work  in  the  Canal  Zone 
and  in  Cuba. 

Have  special  reports  on  sanitary  work  in  the  nearest  harbors. 

Draw  diagrams  illustrating  the  idea  of  alternate  hosts.  Have 
special  reports  on  the  extermination  of  parasites  through  attacks 
upon  intermediate  hosts. 

References.  CHAPIN,  Sources  and  Modes  of  Infection,  pp.  380-417; 
EALAND,  Insects  and  Man,  pp.  88-119,  136-159,  chap,  iv;  HODGE  and 
DAWSON,  Civic  Biology,  chap,  xi ;  JORDAN,  Textbook  of  General  Biology, 
chap,  xxx ;  KELLOGG  and  DOANE,  Economic  Zoology,  pp.  367-377. 

LXXV.    INSECTS   AND  HUMAN  WEALTH 

Collect  specimens  of  useful  and  destructive  insects,  including 
the  various  stages  wherever  possible ;  specimens  of  commercial 
products  and  of  stages  in  industrial  processes ;  specimens  of 
spoiled  materials ;  insecticides. 


84  MANUAL  FOR  TEACHERS 

Have  special  reports  on  life  histories,  injuries,  and  means  of 
fighting  destructive  insects,  and  on  life  histories,  value,  and  means 
of  cultivating  useful  insects.  Study  the  statistical  data.  Give  special 
attention  to  economic  insects  of  local  or  current  interest. 

References.  EALAND,  Insects  and  Man,  chap,  v;  HODGE  and  DAWSON, 
Civic  Biology,  chap,  xii;  KELLOGG,  Insect  Stories;  KELLOGG  and  DOANE, 
Economic  Zoology,  chap.  xvii.  Bulletins  and  reports  of  state  and  United 
States  departments  of  agriculture ;  farmers'  bulletins  and  yearbooks, 
United  States  Department  of  Biology. 


LXXVI.    INSECTS  AND  OTHER  ORGANISMS 

Collect  specimens  of  insects  injurious  to  useful  plants  (complete 
life  histories  if  possible),  together  with  specimens  of  the  plants  in 
question.  Species  of  local  or  current  interest  should  receive  special 
attention.  Have  special  reports  on  life  histories,  extent  of  damage, 
and  means  of  control. 

Make  a  similar  study  of  insects  related  to  economic  animals. 

Wherever  possible,  students  should  be  encouraged  to  mount 
specimens  of  economic  insects  in  arrangements  showing  their 
relations,  —  for  example,  a  twig  with  scales  and  lady-beetle,  or  life 
history  of  gypsy  moth,  life  history  of  calosoma,  and  twig  of  host 
plant. 

Have  special  reports  on  state  and  federal  activities  in  the  culti- 
vation of  insects  for  the  destruction  of  injurious  insects. 

Have  reports  on  spraying  and  other  methods  of  control ;  study 
a  spraying  calendar  etc. 

New  examples  of  the  interrelations  of  species  should  be  re- 
corded ;  study  the  fate  of  introduced  species  of  plants  and  animals, 
and  the  effects  of  introduced  species  upon  native  species. 

References.  EALAND,  Insects  and  Man,  chaps,  ii,  viii ;  HODGE  and 
DAWSON,  Civic  Biology,  chap,  xiv;  KELLOGG  and  DOANE,  Economic 
Zoology,  chaps,  xxx-xxxvii.  Bulletins  of  the  United  States  Bureau  of 
Entomology ;  state  bulletins. 


MANUAL  FOR  TEACHERS  85 

LXXVII.    BIRDS  IN  RELATION  TO  MAN 

Have  field  observations  on  resident  and  migrating  birds.  En- 
courage students  to  become  acquainted  with  the  identities  and 
habits  of  birds,  including  distinctive  songs,  notes  and  calls,  and 
food  plants  and  animals.  The  "  shooting  "  of  birds  with  cameras, 
and  their  "  capture"  by  means  of  suitable  nesting  boxes  etc.,  offer 
worthy  substitutes  for  the  expression  of  primitive  gaming  instincts, 
and  should  be  encouraged.  Have  special  reports  on  life  habits  and 
economics  of  important  birds,  particularly  such  as  are  of  local 
or  current  interest.  Summaries  of  the  various  reports  should  be 
prepared  in  tabular  form,  and  should  include  information  about 
habitats,  seasons,  and  food  plants  and  animals. 

References.  BAYNES,  Wild  Bird  Guests ;  BEEBE,  The  Bird ;  HODGE  and 
DAWSON,  Civic  Biology,  chaps,  iv,  v;  HOLMES,  Animal  Biology,  chap,  xxi; 
JOB,  Domestication  of  Wild  Birds.  Reports  and  farmers'  bulletins,  United 
States  Department  of  Agriculture ;  annual  summaries  of  game  laws,  United 
States  Department  of  Agriculture;  publications  of  the  State  Department  of 
Agriculture  ;  publications  of  the  Audubon  Society. 

LXXVIII.    SOCIAL  LIFE  OF  ORGANISMS 

Have  specimens  illustrating  high  points  in  the  evolutionary 
series,  both  plant  and  animal ;  or  provide  suitable  charts.  The 
emphasis  will  be  upon  the  differentiation  that  follows  upon  inte- 
gration, and  this  should  be  compared  with  the  parallel  process 
observed  in  the  course  of  development  (Chapter  LI  1 1). 

Access  to  a  glass  beehive  or  to  an  ants'  nest  under  glass  is 
desirable.  Have  special  reports  on  division  of  labor  in  ant  and  bee 
colonies.  The  distinction  between  the  automatic  coordinations  that 
obtain  in  such  colonies  and  the  conscious  cooperation  of  various 
human  enterprises  should  be  made  clear. 

References.  FABRE,  Social  Life  in  the  Insect  World;  HODGE  and 
DAWSON,  Civic  Biology,  chap,  xiii ;  HOLMES,  Animal  Biology,  chap,  vii; 
JORDAN  and  KELLOGG,  Evolution  and  Animal  Life,  chap,  xviii ;  KELLOGG, 
American  Insects,  pp.  490-561 ;  KROPOTKIN,  Mutual  Aid;  LUBBOCK,  Ants, 
Wasps,  and  Bees;  MAETERLINCK,  The  Bee;  WHEELER,  Ants,  especially 
chap,  xxiii. 


PART  V.     HEREDITY   AND   EVOLUTION 

LXXIX.    VARIATION 

For  the  study  of  variation,  use  any  organic  structures  available 
in  quantities.  Leaves  are  to  be  obtained  in  all  regions  and  are 
easily  preserved  for  use  in  all  seasons.  Fingers  of  girls  and  boys, 
feathers  of  birds,  claws  or  teeth  of  mammals,  wings  of  insects, 
shells  of  mollusks,  pulse  beats,  ray-flowers,  and  hundreds  of  other 
things  are  just  as  good. 

Have  a  group  of  specimens  matched  as  to  form,  —  for  example, 
maple  leaves  or  finger  prints. 

Make  a  census  of  careful  measurements.  Distribute  the  material 
in  small  boxes,  envelopes,  or  bottles,  with  rulers  or  scales  divided 
to  millimeters.  Instruct  students  to  sort  the  material  into  classes 
representing  differences  of  one  or  two  millimeters.  A  class  of 
ordinary  size  can  obtain  several  hundred  measurements  in  a  short 
time  ;  have  a  committee  of  students  compile  the  results.  If  several 
classes  are  doing  parallel  work,  it  is  worth  while  to  consolidate 
the  data  for  all  and  illustrate  the  increased  smoothness  of  the 
curve  obtained  from  large  numbers.  Have  results  presented 
graphically  as  well  as  in  tables.  Have  them  posted  on  blackboard 
or  chart,  and  if  possible  have  a  copy  made  for  each  student. 

When  the  idea  of  variation  is  fairly  clear,  have  students  bring 
in  examples  of  variations,  physiological  as  well  as  meristic  etc.,  that 
they  have  themselves  observed  among  human  beings  and  among 
other  organisms.  Have  them  suggest  for  each  variation  what  the 
possible  advantage  or  disadvantage  of  extremes  may  be  to  the 
organism.  It  is  worth  while,  in  connection  with  this  study,  to 
have  pupils  record  their  opinions  or  beliefs  as  to  the  causes  of  the 
variations  observed ;  these  views  are  to  furnish  a  basis  for  further 
analysis,  or  hypotheses  for  further  study,  leading  to  a  clearing  up 
of  the  thought.  Examples  of  modifications  in  which  the  causes  are 

86 


MANUAL  FOR  TEACHERS  8/ 

obvious  or  inferred  with  some  degree  of  probability  should  also 
be  collected.  Have  noted  the  modifying  effects  of  disease,  exercise, 
or  disuse,  nutritional  extremes,  habit  formation,  mechanical  injuries, 
injuries  caused  by  insects  or  other  animals,  etc. 

Have  pictures  and  charts  showing  various  breeds  of  domesticated 
animals  and  plants  and  different  varieties  of  cultivated  fruits,  vege- 
tables, and  flowers ;  study  seed  catalogues,  poultry  catalogues,  etc. 
Have  special  reports  on  new  varieties  of  useful  or  fancy  plants  and 
animals,  from  the  United  States  Department  of  Agriculture  year- 
books, from  reports  of  the  nearest  agricultural  experiment  station, 
from  the  State  Department  of  Agriculture,  from  the  reports  of  breed- 
ers' associations,  etc.  Have  a  special  report  on  the  work  of  Burbank. 

References.  BERGEN  and  CALDWELL,  Practical  Botany,  pp.  417-421, 
428-430;  JORDAN  and  KELLOGG,  Evolution  and  Animal  Life,  chaps,  ii,  ix. 
For  the  teacher :  BATESON,  Materials  for  the  Study  of  Evolution ;  DAVEN- 
PORT, Principles  of  Breeding,  chaps,  i-v ;  MORGAN,  Evolution  and  Adap- 
tation, pp.  261-270;  VERNON,  Variation. 

LXXX.    HEREDITY 

In  having  students  bring  in  examples  of  family  resemblances, 
consider  mental  .traits  that  are  not  likely  to  be  the  results  of 
habituation  or  common  experience,  as  well  as  physical  traits.  Simi- 
larities in  voice,  pronounced  likes  or  dislikes,  the  manner  of  folding 
the  hands,  various  mannerisms,  and  physiological  idiosyncrasies 
furnish  interesting  material  for  study  and  comparison.  Uncles  and 
cousins  and  aunts  should  be  considered,  as  well  as  parents  and 
grandparents. 

The  most  valuable  outcome  of  such  studies  should  be  a  clear 
realization  of  the  fact  that  the  resemblance  to  the  two  houses  is 
a  resultant  of  many  complete  resemblances  to  one  side  and  many 
complete  resemblances  to  the  other,  rather  than  a  blending  of  the 
several  characters. 

Have  a  special  report  on  the  alternative  characters  studied  by 
Mendel.  Have  specimens  and  pictures  of  varieties  of  cultivated 
plants  and  animals,  for  study  of  alternative  characters,  students  to 
find  as  many  pairs  as  possible  in  a  given  set  of  individuals. 


88  MANUA^  -FOR  TEACHERS 

Use  blackboard  and  colored  crayons  for  developing  the  Men- 
delian  principles.  Use  checkerboard  diagram  to  show  the  segre- 
gation of  two  or  more  characters.  Where  possible,  show  identity 
of  the  segregation  formula  with  the  algebraic  formula  for  the 
square  of  a  binomial  etc. 

To  make  clear  what  is  meant  by  chance  in  scientific  discussions, 
refer  to  (or  demonstrate  in  class,  or  assign  for  trial  and  report) 
the  experience  of  drawing  cards  from  a  pack  or  of  throwing  a 
coin  or  dice.  The  chances  are  even  that  a  card  drawn  at  random 
will  be  black  or  red ;  that  a  coin  will  fall  heads  up  or  tails  up.  A 
second  throw  of  a  coin  faces  the  same  chances,  and  so  the  third 
and  the  millionth.  But  the  chances  that  all  in  the  series  will  fall 
the  same  way  are  very  small;  and  the  longer  the  series,  the 
smaller  the  chances.  It  is  possible  for  a  coin  to  come  heads  up 
six  times  in  succession;  but  it  is  more  likely  to  come  in  some 
other  succession,  as  there  are  a  great  many  possible  others.  Yet, 
if  we  took  any  one  of  the  others,  the  chances  that  that  one  would 
come  up  are  just  the  same  as  the  chances  that  the  six  heads  would 
come  up.  Now  the  larger  the  number  of  throws,  the  greater  the 
possible  number  of  combinations,  and  the  smaller  the  chances  of 
any  particular  combination  falling  out.  With  three  throws  there  are 
eight  possible  combinations  (23),  any  one  of  which  has  one  chance 
in  eight  of  appearing ;  with  four  throws  there  are  sixteen  possible 
successions  (24),  and  each  has  one  chance  in  sixteen  of  appearing ; 
with  five  throws  there  are  thirty-two  combinations ;  and  so  on,  the 
chances  for  a  special  combination  diminishing  in  geometrical  ratio. 
When  this  idea  is  applied  to  the  combination  of  alternative  characters 
derived  from  the  two»  ancestral  lines,  we  can  see  that  the  chances 
of  a  particular  combination  of  characters  being  duplicated  are 
practically  one  in  infinity. 

References.  For  the  pupils  :  CASTLE,  Heredity  in  Relation  to  Evolution 
and  Animal  Breeding ;  DONCASTER,  Heredity  in  the  Light  of  Recent  Re- 
search ;  GUYER,  Being  Well  Born,  chaps,  i,  iii,  iv ;  HOLMES,  Animal  Biology, 
chap,  xl;  JORDAN  and  KELLOGG,  Evolution  and  Animal  Life,  chap.  x. 
For  the  teacher :  LOCK,  Variation,  Heredity,  and  Evolution,  chaps,  vii, 
Viii;  MORGAN,  Heredity  and  Sex;  PEARSON,  The  Chances  of  Death; 
THOMSON,  Heredity. 


MANUAL  FOR  TEACHERS  89 

LXXXI.   APPLICATIONS  OF  THE  PRINCIPLES  OF  HEREDITY 

Have  special  reports  on  the  economic  and  esthetic  contributions 
of  plant  and  animal  breeding,  from  recent  bulletins  and  current 
publications.  Have  specimens  (where  possible)  and  pictures  of 
new  combinations  brought  about  through  the  systematic  applica- 
tion of  known  facts  and  principles.  Assign  readings  on  eugenics. 

References.  BAILEY,  Plant  Breeding;  BERGEN  and  CALDWELL,  Practi- 
cal Botany,  chap,  xxiii ;  CASTLE,  Heredity  in  Relation  to  Evolution  and 
Animal  Breeding;  DAVENPORT,  Principles  of  Breeding,  chaps,  xix,  xx; 
GUYER,  Being  Well  Born,  chaps,  v,  vii,  x ;  HARWOOD,  New  Creations  in 
Plant  Life.  Yearbooks  and  bulletins  of  the  United  States  Department  of 
Agriculture;  seedsmen's  catalogues.  For  the  teacher:  CASTLE,  COULTER, 
and  others,  Heredity  and  Eugenics ;  DAVENPORT,  Heredity  in  Relation  to 
Eugenics ;  GODDARD,  The  Kallikak  Family. 

LXXXII.   HEREDITY  AND  PROTOPLASM 

It  should  be  clear  that  whatever  is  inherited  is  not  physically 
passed  on,  —  the  red  cow  is  just  as  red  after  the  calf  is  bom 
as  she  was  before ;  and  the  fertilized  egg  of  the  leghorn  has  not 
white  feathers,  —  it  has  no  feathers  at  all,  not  even  in  miniature. 

Get  the  idea  of  the  immortality  of  the  germ  plasm  by  comparing 
with  the  immortality  of  protozoan  protoplasm. 

Show  stained  cells  for  karyokinesis.  Show  stained  egg  cells,  as 
of  Ascaris,  for  chromosomes  and  reduction.  Explain  the  suc- 
cessive steps  in  reduction  and  maturation  divisions  with  the  help 
of  blackboard  diagrams. 

Have  students  make  special  reports  on  sports  among  animals 
and  plants. 

Discussion  of  the  transmission  of  modifications  will  probably 
arise  without  special  stimulation  from  the  teacher, — it  always  does 
if  there  is  the  slightest  occasion.  The  question  of  prenatal  influ- 
ence and  of  the  cause  of  birthmarks  should  also  be  given  a 
chance  if  it  presents  itself. 

References.  CONKLIN,  Heredity  and  Environment  in  the  Development 
of  Man,  chap,  ii ;  GUYER,  Being  Well  Born,  chap,  ii ;  LOCK,  Variation, 
Heredity,  and  Evolution,  chap.  x. 


QO  MANUAL  FOR  TEACHERS 

LXXXIII.    EVOLUTION 

Review  the  idea  of  universality  of  change,  and  emphasize  the 
practical  importance  of  understanding  changes.  Have  students 
give  examples  of  the  use  of  knowledge  to  bring  about  desirable 
change,  to  avoid  undesirable  change,  etc. 

Have  examples  of  continuously  progressive  changes  and  of 
cyclic  changes.  Does  history  repeat  itself  ?  Guard  against  the 
tendency  to  assume  that  we  must  pin  our  faith  to  a  yes  or  a  no 
answer  to  every  question.  There  are  perhaps  other  possibilities, 
and  both  types  of  change  may  exist  side  by  side. 

Show  fossils  peculiar  to  the  region,  and  geographical  varieties 
of  plants  and  animals.  Have  museum  studies  of  fossil  series  and 
of  morphological  series.  Explain  what  a  reconstruction  is,  its 
basis,  and  the  degree  of  its  validity.  Present  alternative  theories 
or  hypotheses  to  account  for  fossils. 

Have  special  readings  (with  reports)  on  the  various  classes  of 
evidence  for  descent  with  modification.  It  is  important  to  avoid 
the  tendency  to  confuse  the  evidence  for  evolution,  considered  as  a 
purely  historical  fact,  with  speculations  concerning  the  mechanism 
of  evolution. 

References.  HOLMES,  Animal  Biology,  chap,  xxviii ;  JORDAN  and 
KELLOGG,  Evolution  and  Animal  Life,  chaps,  iv-ix.  For  the  teacher1: 
LOCK,  Variation,  Heredity,  and  Evolution,  chaps,  i-iii,  v ;  MORGAN, 
Critique  of  the  Theory  of  Evolution,  chap,  i ;  MORGAN,  Evolution  and 
Adaptation,  chaps,  ii,  iii. 

LXXXIV.   APPLICATIONS  AND  THEORIES  OF  EVOLUTION 

The  time  given  by  high-school  or  college  students  to  the  study 
of  evolution  must  justify  itself  not  in  a  resulting  familiarity  with 
theories  or  with  illustrations  and  statistics ;  it  must  justify  itself 
in  a  resulting  attitude  toward  life.  It  may  well  be  that  a  portion 
of  our  population  is  constitutionally  incapable  of  acquiring  a 
dynamic  outlook ;  but  where  there  are  no  constitutional  barriers, 
the  failure  to  acquire  this  dynamic  viewpoint  must  be  charged  to 
the  school  and  specifically  to  the  teachers  of  biology  and  history. 


MANUAL  FOR  TEACHERS  91 

The  study  of  this  section  may  well  take  the  form  of  a  free  dis- 
cussion that  will  ferret  out  lingering  doubts  and  prejudices,  not 
for  the  purpose  of  inculcating  sound  doctrine  on  the  subject  of 
evolution,  but  for  the  purpose  of  getting  the  students  to  feel  the 
majesty  of  the  larger  concepts.  An  academic  analysis  or  a  purely 
intellectual  assent  is  not  sufficient. 

Have  special  reports  and  summaries  on  the  views  of  Lamarck, 
Darwin,  De  Vries.  Have  reports  on  experimental  work  in  evolution. 

References.  CONKLIN,  Heredity  and  Environment,  chap,  v;  GUYER, 
Being  Well  Born,  chap,  x;  HARWOOD,  New  Creations  in  Plant  Life. 
Yearbooks  of  the  United  States  Department  of  Agriculture.  For  the 
teacher:  KELLOGG,  Darwinism  To-day;  LOCK,  Variation,  Heredity,  and 
Evolution,  chap,  x;  MORGAN,  Evolution  and  Adaptation,  chap.  iv. 


PART  VI.  MAN  AND  OTHER  ORGANISMS 

LXXXV.    THE   CLASSIFICATION   OF  ORGANISMS  -  LXXXVI. 
KINDS  OF  PLANTS  —  LXXXVII.   KINDS  OF  ANIMALS 

It  is  not  to  be  expected  that  students  will  attain  to  a  clear  view 
of  the  plant  and  animal  series  from  the  study  of  a  chapter  or  a 
chart.  It  is  only  through  prolonged  association  with  many  forms, 
and  through  constant  thought  upon  similarities  and  differences  and 
relationships,  that  this  is  to  be  attained. 

As  a  means  of  facilitating  acquaintance  with  forms,  present 
constantly  new  specimens  to  illustrate  the  biological  principles 
studied.  These  new  specimens  come  to  the  student  as  laboratory 
material  for  direct  handling ;  as  demonstration  specimens ;  as  exhi- 
bition material  in  the  wall  cases  etc.  of  the  classroom ;  as  objects 
of  observation  in  the  field,  in  museums,  in  the  flower  or  vegetable 
show,  in  the  bird  store,  in  the  menagerie  or  at  the  circus,  in  pictures 
found  in  books  and  magazines  and  upon  the  classroom  walls  etc., 
in  stereopticon  and  motion-picture  views,  and  so  on.  Acquaintance 
with  forms  is  the  beginning ;  classification  and  naming  come  later. 

But  children  begin  to  classify  and  name  almost  as  soon  as  they 
begin  to  speak.  Call  attention  to  the  way  children  name  a  new 
object  in  terms  of  the  familiar  one  which  it  most  resembles. 

Discuss  the  difficulty  of  supplying  enough  common  names,  the 
inadequacy  of  common  names,  and  the  binomial  system  as  applied 
to  proper  names.  The  basis  of  classification  offers  opportunity  for 
making  students  realize  both  the  practical  importance  of  adequate 
classification  and  the  practical  difficulties  of  establishing  a  satisfac- 
tory classification.  For  the  purpose  of  getting  hold  of  principles  of 
classification,  experience  with  postage  stamps,  books,  pottery,  and 
textiles  may  be  quite  as  illuminating  as  experience  with  flowers  or 
fishes  or  frogs.  The  only  advantage  of  experience  with  the  sorting 
of  organisms  lies  in  the  suggestion  of  a  natural  order. 

92 


MANUAL  FOR  TEACHERS  93 

Where  opportunity  and  interest  are  present,  encourage  students  to 
attempt  the  identification  of  species  with  the  aid  of  some  manual. 

As  a  means  of  facilitating  thought  about  relationships,  tables 
and  "  trees  "  similar  to  those  in  the  text  should  be  constantly  be- 
fore the  eyes  of  the  students.  It  is  therefore  desirable  to  have  large 
charts  or  wall  paintings  of  these  fixed  points  wherever  feasible.  It 
is  especially  recommended  that  a  large  portion  of  the  bare  wall, 
above  the  blackboards,  be  devoted  to  outline  "trees"  with  the 
names  of  the  phyla  and  chief  subdivisions,  accompanied  by  outline 
sketches  of  illustrative  forms  from  the  more  familiar  species.  As 
reference  is  made  to  one  or  another  species  of  plant  or  animal 
during  the  course  of  the  year's  study,  the  teacher  may  lightly 
indicate  the  place  of  the  species  in  the  system  as  a  whole,— 
orient  without  elaborating.  More  can  be  achieved  by  this  constant 
repetition  through  a  long  period  than  by  devoting  the  same  amount 
of  time  to  intensive  study  of  charts  and  tables  and  manuals.  En- 
courage students  to  transcribe  portions  of  the  tables  for  special 
groups,  and  to  prepare  larger  diagrams  for  the  classroom  wall. 

Apart  from  the  general  features  of  the  classification  schemes, 
the  significant  point  of  the  discussion  is  the  basis  for  distinguishing 
between  higher  and  lower  plants  and  animals.  This  is  to  be 
considered  with  constant  regard  for  .the  fact  that  the  lowest  are 
quite  as  capable  of  living  as  the  highest,  while  it  is  legitimate  to 
bring  out  the  important  differentia  of  human  life  as  the  highest. 

References.  Manuals  for  the  classification  and  identification  of  common 
flowering  plants  (including  trees),  ferns,  mosses,  common  fungi,  birds, 
insects,  fishes,  reptiles,  batrachians,  and  mammals.  Natural-history  books. 

LXXXVIII.    MAN  AND  HIS  RELATIVES 

This  study  may  serve  as  a  summary  of  the  common  facts  about 
animal  organization  and  functions. 

Use  pictures,  plaster  casts,  relics  of  primitive  man ;  have  museum 
studies.  Have  special  reports  on  traces  of  aborigines  in  the  neigh- 
borhood and  on  current  topics  related  to  man's  ancestry. 

The  argument  is  essentially  a  successive  differentiation  of  man 
from  the  invertebrates  to  the  primates. 


94  MANUAL  FOR  TEACHERS 

The  common  argument  that  the  similarity  between  man  and 
the  lower  primates  appeals  even  to  the  least  intelligent  must  not 
be  pushed  too  far.  The  resemblance  that  appeals  may  be  en- 
tirely superficial.  Young  children  are  quite  satisfied  to  treat  dogs 
and  cats  exactly  as  they  treat  human  beings ;  that  is,  there  is 
enough  similarity  to  appeal  to  their  intelligence.  Savages  attribute 
to  other  animals  and  even  to  inanimate  forces  their  own  type  of 
purpose  and  thought.  This  obvious  similarity  may  thus  prove  too 
much.  It  is  necessary  to  consider  similarities  that  indicate  rela- 
tionship in  the  biological  sense.  That  is,  we  must  separate  what 
men  and  monkeys  have  in  common  with  other  animals  from  what 
they  have  together  that  is  different  from  other  animals ;  and  then  we 
must  consider  the  points  of  difference  between  man  and  other  pri- 
mates, with  a  view  to  determining  whether  these  differences  are 
so  radical  in  kind  or  degree  as  to  preclude  evolutionary  relationship. 

References.  CLODD,  The  Childhood  of  the  World,  chaps,  i-iv ;  DARWIN, 
Descent  of  Man,  chaps,  i,  vi,  vii ;  DUCKWORTH,  Morphology  and  Anthro- 
pology, chaps,  ii,  vii,  viii;  HOLMES,  Animal  Biology,  chap,  xxii ;  HOLMES, 
Evolution  of  Animal  Intelligence,  chaps,  xi-xiii ;  HUXLEY,  Man's  Place  in 
Nature ;  JORDAN  and  KELLOGG,  Evolution  and  Animal  Life,  chap,  xxi ; 
OSBORN,  Man  in  the  Old  Stone  Age;  SPURRELL,  Modern  Man  and  his 
Forerunners,  chaps,  ii,  iii ;  TYLOR,  Anthropology,  chaps,  i-iii ;  WATSON, 
Behavior,  chap.  x. 

LXXXIX.  MAN'S  BRAIN 

Since  the  significant  part  of  this  study  has  to  do  with  the  results 
of  brain  work  rather  than  with  the  structure  and  workings  of  the 
brain,  the  latter  need  not  be  emphasized  unless  there  is  special 
interest  in  the  subject  among  the  students.  Use  a  model  of  the 
human  brain,  and  of  such  other  vertebrate  brains  as  are  to  be  had. 
A  calf's  brain  from  the  butcher  may  be  dissected  for  gross  features. 

Have  special  readings  and  reports  on  museum  studies  on  the 
activities  of  primitive  man,  comparing  them  particularly  with  the 
corresponding  activities  of  other  animals. 

The  question  to  emphasize  is,  How  does  man,  despite  his  struct- 
ural shortcomings,  manage  to  adjust  himself  to  the  inimical  aspects 
of  his  environment,  and  how  does  he  manage  to  supply  his  needs  ? 


MANUAL  FOR  TEACHERS  95 

References.  For  the  pupils :  DARWIN,  Descent  of  Man,  chaps,  iii-v ; 
TYLOR,  Anthropology,  chaps,  iv-xii.  For  the  teacher :  DONALDSON,  The 
Growth  of  the  Brain ;  LANKESTER,  Nature's  Insurgent  Son ;  LOEB,  Com- 
parative Physiology  of  the  Brain. 

XC.   MAN'S  CONQUEST  OF  NATURE  -  XCI.    SCIENCE 
AND  CIVILIZATION 

Man  the  organic  mechanism  is  gradually  replaced  by  man  the 
designer  and  creator.  The  isolated  animal  supplying  his  own  wants 
and  meeting  his  personal  difficulties  is  gradually  replaced  by  a 
member  of  society.  Now  he  hunts  in  groups  and  solves  his  other 
problems  through  interchange  of  service  and  experience,  and 
through  cooperative  effort  in  many  directions.  The  study  of 
biology  merges  into  the  study  of  psychology  and  sociology.  The 
study  of  man  is  no  longer  physiology,  but  anthropology,  ethnology, 
politics,  and  economics. 

The  text  should  be  supplemented  by  assigned  readings  along 
divergent  lines,  depending  upon  the  interests  of  the  students  and 
upon  the  available  material.  Local  relics  of  ancient  times  and  local 
institutions  that  embody  the  highest  achievements  in  the  way  of 
organized  research  are  equally  significant  in  the  final  synthesis. 
The  visit  to  the  museum  of  natural  history  may  well  be  supple- 
mented by  a  visit  to  the  historical  museum  or  to  the  art  museum ; 
for  here,  in  the  consideration  of  man's  achievements,  the  study  of 
nature  passes  into  the  study  of  history  and  art. 

The  study  of  recent  statistical  material  indicating  measurable 
progress  in  man's  conquest  of  his  environment,  and  the  comparison 
of  local  conditions  in  various  respects  with  the  general  conditions, 
will  help  to  fix  the  interest  and  perhaps  to  widen  the  outlook.  The 
emphasis  should  be  finally  upon  the  value  of  civilization  in  terms 
of  life  more  abundant,  to  which  all  science  must  contribute. 

References.  CLODD,  The  Childhood  of  the  World;  CONN,  Social 
Heredity  and  Social  Evolution;  HODGE  and  DAWSON,  Civic  Biology, 
chaps,  xxxi-xxxii ;  KELLICOTT,  Social  Direction  of  Human  Evolution ; 
LANKESTER,  Nature's  Insurgent  Son;  SPURRELL,  Modern  Man,  chaps,  iv- 
vii ;  TYLOR,  Anthropology,  chaps,  xiii-xvi.  Current  reports  of  progress  in 
applied  knowledge. 


SEP 


'OLOGY  LIBRARY 

1932 


31  1935 


2  1964 


i<»2 


JIOLOGY 
LIBRARY 

., 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


